Thursday, August 11, 2011

Review of the 2009 Annual report from the National Joint Registry of Australia (part 5 of 5)

This is the 5th post re the joint registry data on the revision history and performance records on the hips. I specifically was interested in the Depuy Pinnacale as that is the recommended option for my revision and in the process incorporated the data from the Depuy ASR recalled hip.

This section is based on the analysis of 27, 515  hip revision procedures recorded by the registry up to and including the 31st of Dec 2008.  Included in this group of revisions is a sub group containing 5732 first revisions of primary hip procedures.

I found two interesting things in this section:
  • The description of  major vs minor hip surgery. This is important because when you are comparing outcomes of surgeries, it is important to know what kind of revision is done.  Many people who have reported revisions on this blog have had a really hard time with the revision so I am postulating that the revisions they had were classified as MAJOR surgeries.  My surgeon offered that I would recover just fine from the revision as he intended to only replace a few pieces of the total hip in which case, my surgery would likely be classified as MINOR surgery.

  • The discussion surrounding the likelihood of further revisions if you are having minor surgery. This of course was quite surprising to me .

1.  A major revision involves the removal and or replacement of a major component.

2.  A major component is defined as  one that interfaces with the bone.

3.  The components that interface with the bone are either the femoral stem or the acetabular cup (shell.)

4.  When only one of the two major components are replaced, it is considered a partial major revision.

5.  If both are replaced, it is considered to be a total major revision.

6.  A minor revision is is one where the component being replaced has no contact with a bone:
  • exchange of a femoral head
  • exchange of a femoral neck
  • exchange of an acetabular insert
7.  Most revisions recorded in this registry are categorized as major revisions: 85.4%!

8.  Of the major revisions, 35.7% involve revision of both the femoral stem and acetabular cup or shell.

9.  Most major revisions involve revision of only one of the major components: 58.4%

10  Femoral stem revisions account for 21% of all major revisions.

11.  Minor revisions account for 14.6% of all revision procedures.

12.  70% of the minor revisions involve exchange of both the head and insert.

13.  The most common reason for revision is loosening of the hip (56.4%.)

14.  Minor revisions have a greater risk of subsequent revision compared to major.  At 3 years post revision, the cumulative re revision is is almost 18%!

15.  The major revision/ re revision rate over the same 3 year period is about 9%.

16.  The revision rates by fixations from 1999-2008:
  • Acetabular only: 37.4%
  • THR (femoral and acetabular): 35.7%
  • Femoral only 21%

Reviewing both the Australian and the England and Wales 2009 report provided some perspective on the rate of revisions and the surfacing of the Depuy ASR issues.  I will look at 2010 in the comming week.

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