Polymotion - Worth the wait in USA (vs BHR)?

[Seth]

Hello Everyone. I am hoping to get some information from this group on the new Polymotion implant that has been invented by McMinn. I'm in the USA and trying to decide whether it is worth to wait and undergo a Polymotion clinical trial or to just get the BHR (or Gross's BioMet implant) now. I'm truly mixed on this decision due to my questions / comments below. Any help is appreciated.

Some context: I'm a younger male ~ 50, good bones in general, 6'1" (i.e. 185 cm), in the USA, been researching resurfacing for about 8 months, I'm a good candidate for a BHR (or BioMet)

Please note, I could be off on some facts here and will try my best to present facts as I understand them. Any insights on these questions would be greatly appreciated. In return, I'm happy to share my research with this group on my own journey.

Here are my Q's and comments:

   Â· STRESS SHIELDING: My main motivation in exploring the Polymotion device is it's potential for less stress shielding than the BHR (or Tom Gross's BioMet) since it is softer than metal on metal. I.e. I think I've overcome my concern with metallosis. That said, I cannot find any good data whether the BHR (or Tom Gross's BioMet) creates an issue with stress shielding, say after 20 years. The BHR has been around for a long time, I believe since 1997 so by now in 2024 there should be 27 years of data, including on the metal-metal effects on stress shielding. I heard from one highly trusted/qualified person that the MAIN issue with the BHR is stress shielding and, after about 20 years, it can create issues on the acetabular cup side because the bone would be unduly shielded from the normal load needed to maintain density because the metal is too hard. According to this source, one should not expect to gain 30-40 years out of a BHR (or BioMet) and the bigger issue to me is the longer term weakness in bone density. All this makes sense to me, and hence my main motivation of exploring the Polymotion is because titanium is a lot softer than metal and would probably have fewer effects on long term stress shielding. That said, I cannot seem to find any data on the 20+ year effect of stress shielding for the BHR or BioMet. Either it is not an issue or that potential problem hasn't been tracked?
   Â· POLYMOTION 9 YEAR DATA: It seems like the first Polymotion patient was in 2015, so there would be 9 years of data so far (in theory). That said, I am having difficulty finding any data on success of the implant from 2015-2024. From my understanding, the implant has been used in a number of countries in Europe, UK, Australia, Canada, and was hoping there would be some outcomes from the clinical trials from those respective countries that undertook for the Polymotion implant.
   Â· POLYMOTION USA CLINICAL TRIAL: I'm in the USA and Polymotion is pending FDA clearance for clinical trials. That said, I cannot find any updates on when this could happen. I've heard informally it could happen as early as this summer of 2024 and cannot find any information online about it.
   Â· TRAINING FOR NEW SURGEONS: Seems like new surgeons would need special training on performing this procedure, at least for the first few times, probably from McMinn himself. The reason being there are two spiked holes that are needed to be drilled on the acetabular side. This appears to be critical for accurate placement of the cup and there appear to be no forgiveness for error. I.e. I believe the surgeon needs to get it right the first time and there is no room for fine tuning (unlike a BHR or BioMet). To me, this means there is some risk with the surgeon's inexperience with the implant -- although I could be wrong.
   Â· MATERIALS: Is the Polymotion implant 100% pure X-linked (better for wear) or does it also have regular poly too (regular poly better for durability, function)? I believe I saw an analysis by McMinn showing one implant that was a combination of the two -- most of it being X linked in the inside better for wear and the outer edge being regular poly which is better for function/durability. I could see the transition between the two in a talk presented by McMinn at one point although it's not clear if the Polymotion has both types of poly or just one. If just one type of poly, has the issue of durability been addressed on the outer side of the cup? My understanding is that while X-linked poly is great for wear, it can crack easier which is what led to a concept of using both polys at one point. Again, I could be off here.
   Â· SHAPE: Is the Polymotion a constant thickness or crescent shaped? I looks like a constant 3mm thickness and because it is thin like the BHR there is not a need to consider a crescent shape.
   Â· INSURANCE: Would a polymotion implant clinical trial be covered by health insurance? I'm in the USA. My guess is a portion of it could be picked up by the sponsor and it is unclear to me if my health insurance company will pick up the bill on rest given it would be considered experimental.
   Â· REVISIONS: In the case of a revision, I believe you can remove/replace the Polymotion easier, and possibly undergo another resurfacing. My understanding is it is much harder to remove a BHR (or BioMet) and after that removal a total hip replacement would be necessary and hence another resurfacing would not be a possibility.
   Â· NICKEL: Polymotion seems to avoid any issues with Nickel which is my other motivation to explore it.

Again, I appreciate everyone's thoughts on any of the points above.

Thank you!
Seth

[BilateralRecerf]

Why not explore ceramic options?
-  It is the most durable option
- no risks that come with metal.
- Not in the usa market yet, get one from europe or canada or wait for fda approval. https://surfacehippy.info/ceramic-on-ceramic-hip-resurfacing-surgeons/

Other similar polymotion option by dr. Pritchett is forbidden to use and maybe lawsuits going on

https://www.fda.gov/medical-devices/safety-communications/do-not-use-synovo-total-hip-resurfacing-system-fda-safety-communication

[JEL]

Hi Seth

I had a right Polymotion end of sept 2023 in NZ and it’s going well, back doing pretty much anything I want now although easing back in to squash/tennis and still building strength but have no pain which is amazing. I’m 6ft 5in 105kg. Went with the Polymotion as I had skin reaction from my watch band which they thought could have been nickle but they don’t do LTT here so I never had any actual testing. I had initially enquired about Polymotion but it wasn’t an option, hip deteriorated quite quickly towards the end, I figured there was very low risk for any in vivo metal reaction (43 y/o male) so went to lock in BHR but I was lucky with timing as my surgeon had just been to a Jointmedica event re Polymoton and said it would be available soon so I waited a few months and got it done.

I’ll attempt to answer what I can from below but I’m no doubt bias having had the Polymotion. Based on the data MoM BHR/Biomet are the gold standard. Hoping in 20 years I’m here saying I backed the right horse, so far so good…

STRESS SHIELDING

This was a major consideration for me â€" Haven’t seen any joint registry data on stress shielding but it has been referenced in McMinn’s presentations and he’s said it makes a revision tough if the acetabulum has eroded and I assume I’ll need a revision at some stage. It makes sense if the XLPE density is similar to bone it will transfer the load through and hopefully protect the roof for future (Wolfs law). That said BHR is at 25 years and if it was a major problem I’m sure there would be more data.

POLYMOTION 9 YEAR DATA

I’ve only seen what has been presented on the online presentations. I think they said they had a 95% survival but the new Polymotion with the spiked cup and revised Titanium coating (infused to poly rather than plasma spray) has only been implanted since early 2023. That’s the one with FDA breakthrough device designation.

POLYMOTION USA CLINICAL TRIAL

Unsure in the US but you maybe able to contact Jointmedica/Exactech to get a gauge on time. I guess they’ll be pulling all the data together on the new device and probably present when they have at east a few years data.

TRAINING FOR NEW SURGEONS
My surgeon had put one in a cadaver prior to me but Sharat Kusuma flew over to assist with the surgery and they got it spot on in terms of placement. They’ll want to make sure any surgeon implanting knows exactly what they are doing.

MATERIALS

Cup is XLPE infused with Vit E (UHMWXLPE) they haven’t disclosed the process e.g. annealed/remelted/radiation levels etc that I can see. In terms of wear characteristics Vit E XLPE looks great in THR.

SHAPE

I was shown an implant prior to surgery and I’ve seen x-rays, there might be a slight taper towards the edge but looks fairly constant. There are 3ml and 4ml cup options, mine is 3ml. Head is CoCr with slight modifications from BHR shorter stem and allows bone cement to exit easier (sounds like compression of excess bone cement in BHR may have contributed towards some failures)

INSURANCE

Unsure but insurance covered mine here no questions asked.

REVISIONS

Looks a lot easier to ream out and minimise bone loss compared to removing MoM, there’s a video on one of McMinn’s presentations and it takes about 3min.

NICKEL

They mentioned there were no elevated metal levels on the previous trial data, I haven’ had mine tested but not something I’m worried about with MoP.

Finally, re the previous comment about the syno preserve FDA warning, from what I’ve read it’s due to the company making changes to the design without advising FDA. There are no similarities other than the material they use in the shell. Closest comparable would be The Mathys RM Pressfit Vitamys used in THR which there are a few studies on, about 5-6 years of data on the Vit E version published which looks promising.

Hope some of that helps, good luck and hope you’re pain free soon no matter what device you go with!

[Seth]

Thank you!

Yes, McMinn mentions in one of his videos that Stress Shielding is a very real issue which can l lead to a difficult revision on the acetabular if there is significant reduction in bone density on the acetabular side. He shows one image in one of his videos although it is unclear to me if this is a known widespread effect or isolated. He mentions a deterioration of 20-33% in the acetabular roof after 1.2 years following the "trilogy cup." The exact paper that discusses this is here although unsure if this is here:

https://journals.lww.com/jbjsjournal/abstract/2001/04000/bone_density_adjacent_to_press_fit_acetabular.7.aspx

   "Baseline density was measured within the first five days following the total hip arthroplasty. Ipsilateral density measurements were repeated at an average of 1.28 years postoperatively…. Relative declines in mean density ranged from 33% to 20% of the baseline values."

Ceramic has about double the elastic modulus of metal (i.e. it is even harder) so my guess is ceramic would make the stress shielding topic even worse. I also heard about squeaking although maybe that is solved by now.

The long term effects on stress shielding seems to be a real issue (as alluded to by McMinn) and my top concern. I wonder if there is any data on this to show the quality of the acetabular roof with a BHR and comparing that to a MoP total hip? Admittedly, I'm fishing for 25+ year BHR results to get myself comfortable that stress shielding, like metallosis, is small risk. :-)

I've looked into Pritchett's implant a bit. He is a great surgeon indeed - very passionate one of the best. One thing that is a bit of concern for me is that PoM implant is quite thick -- which would mean taking away a lot more bone on the acetabular size. From my research, it is best, whenever possible, to preserve the acetabular bone stock as much as possible to minimize the complications of a potential revision (which is already complex). That said, his acetabular cup I believe is titanum, comparable to the Polymotion so there would be less stress shielding with his approach.

I would be grateful to know about the online presentation showing the 95% survival rate for the Polymotion. I can't seem to find that. That's pretty good (although not as good as Gross's numbers).

Great point on the Polymotion 9-year data. I did not know the Polymotion spiked cup was just released last year in 2023.

What I do like about the Polymotion 3 mm implant is that it seems to mimic the materials used in a THR with X-linked poly with a titanium cup. That data has been around for a long time and Poly with titanium seems to be the standard in a THR. My thinking is if we can get the upside of that (i.e. lesser stress shielding + no metal + no nickel), along with maximum bone preservation as in the BHR, it could be a significant leap forward. Of course there is a risk bc it is new. I'm considering rolling the dice if one of the Polymotion folks would fly to the USA to supervise. Else I may consider going abroad although that adds operational complexity with travel, follow up, insurance, etc.

[JEL]

https://www.jointmedica.com/resources?wix-vod-video-id=53adc2934b954cb898e48b4839984cf7&wix-vod-comp-id=comp-lowy8bzh

Might be in that link or one from the ITSA2023, can't remember where I heard it, I've watched so many.

You may have seen it but it gives a bit of info at the end as to the changes they made and why on the polymotion. At the time of my surgery I was told there had been no failures of the new version, early days but a good start. Jointmedica look to to be upscaling their business in terms of recruitment/personal so they must be fairly confident they're on to a good thing... Here's hoping :-)

[Seth]

I just revisited the story of Elaine Williams on surface hippy who had her Polymotion implant by McMinn in 2015.

https://surfacehippy.info/elaine-williams-first-polymotion-hip-resurfacing-patient-with-mr-mcminn-2015/

A couple of questions that came to mind:

   1) Shouldn't we have 9 years of Polymotion data for patients during Elaine's time by now? Looks like the latest Polymotion generation is the  2023 FDA Breakthrough version and I'd be interested to know the outcomes regardless of which generation. And I would assume the implant would just get better with each revision.

   2) Assuming patients during Eliane's time were also part of a clinical trial, would JointMedica/Exactech be required to share all prior data?

JointMedica/Exactech seems to indicate they will start clinical trials in the USA soon. Trying to get more information on that.

My personal motivation is to explore the Polymotion for 2 possible advantages over the BHR: 1) ability to revise via another HRA instead of a THR, 2) less stress shielding which means a stronger acetabular and less complications on revision. Not sure if those are enough to take the plunge as I'm bigger boned and not concerned with metal-sensitivity (or ionization). For others with metal-sensitivities or smaller sizes, I suppose PolyMotion becomes a more compelling case. That said, I assume the advantages in 1) and 2) would be the same for all patients regardless of bone size or metal sensitivity.

Thanks.

[Pat Walter]

Yes, the trials for the Polymotion are starting in the US.  I don't know all the surgeons yet.  I should get a list pretty soon.  I just had a conference call with JointMedica last Tuesday. They are very excited to get their trials running in the US.  The Device is approved in New Zealand and they are very proud of that.  I will have more information in the future.
Interesting that one of the doctors in the trial is Dr. Gross.  Here is information from his website:
https://www.grossortho.com/polymotion-hip-resurfacing-hr-device
I have two patient stories posted here:   

https://surfacehippy.info/category/hip-resurfacing/hip-resurfacing-devices/jointmedicas-polymotion-hip-resurfacing-system/
When I receive information that I can share - I will post it.
Pat