Monday, March 19, 2012

Wear Analysis report for explanted hip (connie's hip.) part 1 of x.

Not sure how many of you have read your wear analysis report from your hip explant.  This is a report that you have to either get through your lawyer if you have one or identify a company that can  run this test.

The purpose of the report is to identify how much metal has worn off the implant while it is in your body. (Of course you can only do this with explants as the hip has to be sent to a lab and examined.) 

Why would you do this? Likely you wouldn't unless you have retained a litigator and intend to go to court or unless you have other medical conditions and you and/or your medical team might want to rule out the metals as being causative or contributory to the new condition.

Here is the bottom line of this report for my hip:

I had a discussion with the lab that ran this as the conclusion of this report was that my hip was "heavily worn and it is likely that the high volumes of metal wear from the articulating surfaces of the femoral head and acetabular cup have been linked with clinical problems."

 I asked for clarification on this.

1.  The data used to benchmark "wear" is taken from the Lord paper which was published in 2/2011.  I will review that paper tomorrow as a part two of this report.

2.  From that paper, it has been found that one 3mm3/year of wear is reached then the that ASR joint will fail.  So clinical problems with ASRs begin at approximately 3mm3/year. (As you can see above, my average ware rate is 21.8mm3/year.)

3.  Remember, even though my wear rate is considered heavily worn, I had no external symptoms which plays into that recently published paper by Wynn-Jones et al in 2011:  Silent tissue pathology is common with MOM hip artheroplasty.

4.  Although the taper wear volume on my hip was comparatively small compared with the volume of  metal released from the articulating surfaces, they stated the effects should not be ignored. I have discussed this issue in previous posts where the question of taper ware (area between the stem and the head)  was raised as being equal to or more important than the wear from the articulating surfaces (area between the cup and the ball or head.)...I think I got that right.

I'll see if I can figure out how to clip out some of the pictures of the hip.  Will also look at the Lord paper tomorrow.

Hope this helps you see what the bottom line is in looking at a wear report through an engineering lab with sophisticated equipment to run this sort of test.  If you decide to undertake a test like this, research the lab first.  There are not many labs that have the appropriate equipment to run tests like this.



  1. Hi Connie
    Can you give all the contact information for the lab used?

  2. I need to get permission from them. Will request that.


  3. Permission granted to print.

    You can see the video of the interview I published on march 11th with Dr Joyce:

    Dr. Tom Joyce Phd
    Newcastle University
    Stephenson Building
    Department of Mechanical Engineering
    Newcastle upon Tyne
    NE1 7RU