Wednesday, August 17, 2011

Review of the 2010 Australian Joint Registry Results for hips having higher than anticipated revision rates(4 of 4) : The Depuy ASR

1)  Reason for revision of the ASR vs other total conventional hips


Revision diagnosis
 ASR number
ASR
%revision
ASR
% of all primary procedures
Other conventional hips
(number)
Other conventional hip revisions
 (% revision)
Other conventional hips
(% primary)
Loosening/lysis
92
43.8%
2.1%
1427
29.3%
.9%
Prosthesis
dislocation
15
7.1%
.3%
1385
28.5%
.8%
infection
42
20%
1%
804
16.5%
.5%
fracture
19
9%
.4%
725
14.9%
.4%
pain
7
3.3%
.2%
97
2%
.1%
Other (14 categories)
35
16%
.9%
429
1%
0
revisions
210
100%
4.8%
4867
100%
2.9%
Primary
4406


16,698



[ comments from connie: When you look at these numbers, you begin to see why a surgeon would have used this  Depuy ASR device.  This chart shows several likely reasons:
  • Prosthesis dislocation is 400% higher in the Other hips vs Depuy ASR
  • Fracture is 60% higher in the other hips vs the Depuy ASR
On the other side of the equation, you can see the downside:
  • loosening of the prosthesis and lysis is about 70% higher in the Depuy ASR (Lysis (Greek λύσις, lýsis from lýein "to separate") refers to the breaking down of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity)
You have to pick your risks.  The surgeon likely looked at younger patients who were more active-like me- and chose the hip with the lower chance of dislocating and fracture.  Unfortunately, as it turned out, in the long run, the lysis turned out to be a major issue.

This little exercise reaffirms the concept that with every reward in medicine there are risks.  Somehow, surgeons have to balance them out sometimes absent complete information.]

2.  Number of revisions of ARS by year of implant (remember the data here is all from Australia joint registry.)  Note:  Primary procedures performed in later years have had less follow up time therefore the number revised is expected to be less than the number revised in early years which is why you wouldn't calculate percents.

In the early years, you can see that the percents are relatively high comparatively:
  • 4.7% /2004
  • 7%/ 2005
Year of Implant
Number revised
Total Number
2004
4
84
2005
41
583
2006
60
958
2007
56
2284
2008
45
1172
2009
4
425
total
210
4406

this is kind of interesting as well because if you look at the calculation of these rates in the last few posts, something seems to be incongruous...not sure what?  Likely the cumulative numbers would be better to look at not the annual numbers.  These were published in the last few posts.

Anyway, this was very interesting especially the first point above.  It provides perspective on the surgeon's dilemma doesn't it? 



1 comment:

  1. where is Smith and Nephew getting their statis from, McMinns original controlled patient group of 2385?? If they are how tainted is this information seeing it is coming from a single source, and McMinn, the partial inventor of the BHR also had a financial interest in this device once it was approved to be marketed in the USA

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