poly hip HR

[lyn]

 Does anyone know why there is not much discussion about HR with a polyethylene component. I only know of Dr. Pritchett who is doing this. I have gotten 3 opions from different Doctors. 1 said he would do it if I insisted on it but recommended a THR. The other one said I would be a candidate for HR. The last one said he felt I was too small at 42mm. I feel that all the doctors have given me their best advice. But I have to admit I'm concerned with the MOM issue. I'm interested in learning more about the poly hip and have read Dr. Pritchett article on it.  I'm kinda wandering out there trying to figure what to do. If anyone has any more info on the poly hip HR please let me know. Thanks, lyn   

[John C]

Like most people here, I have no medical training, but based on my own reading, you might look into the following ideas.
You might want to look into some of the papers on the early resurfacings from the 70's. The majority of these used some sort of poly on the acetabular side. There were very high failure rates (I seem to remember that it was well over 40%). Many people believe that the cause of the failures was high amounts of poly wear debris, which led to osteolysis and component loosening. Some of Dr. Pritchett's papers on early resurfacing do a very thorough job of covering this era, and the results. The general conclusion was that large femoral heads caused excessive poly wear, as compared to small head THRs using poly. This is the reason that resurfacing went to MOM, to avoid the poly wear problem. In fact one of Dr Pritchett's papers regarding that time frame, described that while the resurfacings with poly ended up with a very high failure rate, the MOM results from his study in that period showed a roughly 0% failure rate at 20 years.
From what I have read, we are now seeing a small and careful return of poly to resurfacing with two changes that hopefully will avoid what happened the first time around. Everyone agrees that the new polys have much better wear rates than those from the seventies, and since the poly wear is believed to have been associated with larger head sizes, it is only being suggested for the smaller head sizes in resurfacing.
I think that you do not hear much discussion today about using poly in resurfacings, because most of the doctors that were involved in, or have studied, that early era of poly resurfacings are scared to repeat that experience. From what little I have read about it, it seems initially that Dr Pritchett may have succeeded in finding the right combination of stronger polys, and smaller head selection, to have beaten the old problem and achieve a good success rate. I think that most people are wanting to stand back and watch for a while to see how this goes, before getting involved in too much discussion.

[Luanna]

Greetings lyn,
There is not much discussion because poly has a bad rap from old polyethylene that wore very badly years ago. I have a cross linked poly liner inside a titanium cup along with a BHR femoral metal ball and it was installed by Dr. Pritchett. He believes that most surgeons have to do what they feel is best based on their experience. He has some strong opinions based on his years of experience and it seems to go against the grain right now but he has do what he feels is best for his patients. One of his colleagues a very strong proponent of metal on metal is using this same metal/ poly liner and BHR metal femoral component combination in some small-boned women as well. So, it will be interesting to see how this whole debate plays itself out over the next few years.

Dr. Pritchett doesn't believe that many folks will quickly jump on board his bandwagon for the metal with poly acetabular cup anytime soon but he has been through so many trends and different component fads over the years and he sees it as the best option there is for small boned women at the moment. In one of our appointments he said that ideally he'd like to see a ceramic ball with the titanium/poly liner. But to make that happen would take lots of $ for testing and there is not enough support yet to move that idea forward.

It sounds like the surgeons get together and really challenge each other about their choices in off hours at their annual conferences. I'd love to be a fly on the wall listening to their debates.

Luanna

[Dannywayoflife]

There will be a ceramic hr device released to the Market soon. But to be fair it's still going to be a long time before it will have the data and track record that the current devices made from vitallium have. My concern with ceramic would be fracture and squeaking

[Luanna]

Hi Danny,
Will it be ceramic on ceramic? Or ceramic ball on metal/poly liner cup? Just curious. Also, do you know who is making this product? Did you hear about it from Mr. Treacy? Because of the old poly products and old ceramic products that had high fail rates it will take quite a bit of time before anyone jumps on board. Time will tell.

I like the idea of metal on metal as it seems like it would be impossible to wear out the device.

Thanks,
Luanna

[bluedevilsadvocate]

According to Mr. McMinn's website, there is a BMHR with a ceramic femoral component, which McMinn has used in 19 patients.  The website indicates that each ceramic femoral compenent is customized for the specific patient, which is interesting.  These have been in use for only a short time, so long-term results aren't available yet.

[Luanna]

Bluedevil - thanks for the info. Mr. McMinn is also installing my components on some small-boned women for HRs. Dr. Pritchett said that Mr. McMinn had done about 20 of them as of August 30th. Interesting about the ceramic for BMHRs. Customizing components in a mix and match way may be the wave of the future. Stryker is making components that can be used with a variety of other components.

lyn - just fyi I'm a 40mm so even smaller than you. I feel really blessed to have the opportunity to have an HR. My poly liner and BHR femoral components work well. I don't have any sense of having implants at all. Everything is smooth and even. People with metal on metal often talk about having a clunking sensation and I can't relate to what they are describing. Feel kind of left out... but glad to have an HR no matter the components. According to Davina who just had the same components put in, Dr. P has been doing these for over 8 years with very few failures.

Luanna

[Dannywayoflife]

Luanna,
           I know finsbury who originally manufactored the bhr for midmedtec are close to releasing a CoC resurfacing. I also believe that S&N are going to release one soon. I had some email contact with one of the surgeons developing the finsbury delta surf.
My question is though why do small boned women suffer issues with MoM resurfacing and yet there ok with thr or other materials?
 

[lyn]

 Thanks for the feedback and info I really appreciate it. I spoke to Dr. Prichett by phone . I feel like I should fly up and speak to him in person as well. I think I'm either going to have a mom hr or try a poly hr. I really want to avoid a THR and I'm thinking I might as well try a HR of some sort- if it fails it will a least buy me a few more years and the revisions that they are now doing seem to be something the Dr.'s can deal with a bit easier.
Thanks, lyn

[strost]

Hi Lyn,
I'm in the same boat as you with trying to decide what kind of device to put in my body - especially being a petite woman. I don't know the size I would need though. I'm also not thrilled with metal on metal. Dr Brooks and Dr Gross are both willing to do metal on metal in petite women. I also spoke to Dr Pritchett and liked the fact that he was not using the metal on metal. It does not look like he takes my insurance though. I'm also considering a total hip that is titatium, stainless, polyethene with a ceramic head.

My head is spinning. Know I definitely want a skilled surgeon, but want to be smart about what I put in my body. Dr Pritchett said he has done some revisions on perfectly placed metal on metal hips.

Keep us posted on what else you find out.
Thanks,
Susan

[Luanna]

Keep doing your research. You will come up with the best solution for your particular situation. You have to be comfortable with your choices and your surgeon.

Luanna

[Tin Soldier]

Lyn - glad you heard from Luanna, she knows the poly/metal HR deal. 

I'm a Pritchett fan, but if you haven't already, you might consider getting another opinion from Gross or others, as strost did.  Maybe some of the joint registrys or McMinn or Gross have data specific to small-boned women and failure rates.  Maybe that would help you help you decide.  Although, as Luanna says, Pritchett has has really good results with the poly on metal implant.  I have to rely on his expertiese.  As John says, Pritchett has been through the various iterations on HR and has first-hand experience with them.  I beleive some of the newer materials that are being tested that Pritchett is interested in is ceramic on polyurethane.  I can envision them right now, lined up in some far off lab in Michigan, cycling millions and millions of times.   

My question is though why do small boned women suffer issues with MoM resurfacing and yet there ok with thr or other materials?

Good question Danny.  Maybe because with the THR, docs orders are not to run or do impact load type activities.

So Strost - I think based on that thought, stick with the HR and you won't be relegated to limiting your activity.   

[Dannywayoflife]

Tin you may well be correct about the advisories not to be active. My gut tells me tho that something Mcminn touched on in one of his interviews with vicky. The placement had to be different for young women because of dysplasia. I think that this may be why a "perfectly" place device might be causing problems in small boned women. As it's something that I believe Mcminn etc only realised fairly recently.

[Tin Soldier]

Good point.  This makes me think about the idea that area of a sphere (or hemisphere, in this case) almost exponentially increases as the diameter increases, thus the pressure per area decreases significantly with a slight increase in the diameter.  The more pressure per area and the less amount of area to absorb the wear, the more wear you get.  We've discussed this before I think.  Also, there are a few studies I've read on this subject.  Long story short, the smaller components are more likely to have more wear than the larger.  Seems pretty intuitive actually.     

BTW - McMinn's book (Modern Hip Resurfacing) has a really interesting section on his early work using various prosthesis testing devices in the early days. 

[einreb]

I feel that all the doctors have given me their best advice. But I have to admit I'm concerned with the MOM issue.

First 1000 un-cemented components and 2 adverse wear related failures... apparently addressed with success via an inter-operative x-ray to get proper angle... 

http://www.grossortho.com/forms/HSR%20consent%208_2011.pdf

Just food for thought. 

-Bernie

[Dannywayoflife]

Good point.  This makes me think about the idea that area of a sphere (or hemisphere, in this case) almost exponentially increases as the diameter increases, thus the pressure per area decreases significantly with a slight increase in the diameter.  The more pressure per area and the less amount of area to absorb the wear, the more wear you get.  We've discussed this before I think.  Also, there are a few studies I've read on this subject.  Long story short, the smaller components are more likely to have more wear than the larger.  Seems pretty intuitive actually.     

BTW - McMinn's book (Modern Hip Resurfacing) has a really interesting section on his early work using various prosthesis testing devices in the early days.

I have a copy of a booklet written by Mcminn & Treacy about the development of the bhr. Some of the torture tests defy belief!!

[lyn]

 Hi Susan,

 I will keep you posted on what I find out. I know I will have a consult with Pritchett and Gross. I'm 50yrs old and have at least come to the conclusion that I will either have a poly hip HR or a MOM.  I want to go back to playing tennis. Dr. Pritchett and Dr Gross have both said no restrictions after recoup. I think I will have a better idea after speaking to both doctors in person. If you can do that, that will probably help you decide, I would think.  What I would like to know is what is the percentage of successful HR (MOM) with little or no adverse wear issues with small boned women. We here so much of the poor results with small boned women, but there must be a percentage of successful MOM HR's. I think the more info we get the better we will be able to decide what is best for us. That is what is so nice about this discussion group its helps you think of things you other wise maybe would not have. Hang in there and take one day at a time.

[hernanu]

Hi Lyn - here's information over ten years from the full 2011 Australian Registry as posted by Pat:

http://www.surfacehippy.info/pdf/aoanjrreport2011.pdf

The information over 10 years for women - cumulative, it adds in the previous years revisions. :
(from page 96 of the report)


Less than 50 mm in head size

0 years - 2.6 (2.1, 3.3)  1 year - 5.3 (4.5, 6.3)   5 years - 8.0 (7.0, 9.2)  7 years - 11.2 (9.8, 12.7)

So that means that at 1 year, 2.7% more were revised, at 5 years, 2.7% more were revised, at 7 years, 3.2% more were revised.

Greater than 50 mm in head size:
0 years - 0.5 (0.1, 1.8 )  1 year - 1.2 (0.5, 2.9)   5 years - 2.2 (1.1, 4.3)   7 years - 3.5 (1.9, 6.4)


So in this, smaller boned (and so smaller prosthesis) were revised at a higher rate.

Some things to keep in mind:

• The numbers were all ages rolled in together, there is data there broken down by age.
• The data included the now recalled ASR results, which significantly (17.9%) impacted women.
• The data covered all surgeons, does not identify surgeons with > 500 procedures, for example.

For comparison, here are the revision figures for a THR by head size:

(Pg. 73)

For heads < 32 mm

1 year - 1.4 (1.0, 1.9) 3 years - 3.1 (2.4, 3.9) 5 years - 3.9 (3.2, 4.9)  7 years - 4.5 (3.7, 5.6)

For heads > 32 mm

1 year - 2.0 (1.7, 2.4) 3 years - 5.7 (5.1, 6.4)  5 years - 8.6 (7.8, 9.6) 7 years - 10.9 (9.6, 12.4)

In comparison of HRs with THRs, at 5 and 7 years the revision rates became comparable.

Hope that helps.

[lyn]

Thank you Hernanu,
That was very nice of you to break the numbers down like that. It was helpful. And I feel Dr. Gross has some impressive statistics. He is very confident. He has given me very good percentages on what he feels are my odds for MOM wear and femoral neck fracture. Im looking forward to speaking with him in person. Thanks again for the info..lyn 

[imgetinold]

Lyn,

You cannot go wrong with Dr. Gross.  And, I think that unless you have a specific metal allergy, the revision rate for metal ions is extremely low.  There is no specific statistic for revisions due to metal ions AFTER they all figured out the cup angle issue.  Once they can start tracking that, I imagine it will be negligible. 

Good luck with your decision.