Most of the time, for fatigue tests you'd read that range as the minimum load was 135N and maximum was 1350N and that each cycle went from minimum to maximum. They didn't specify that, but that's the way I report fatigue test parameter when I perform them on the product (non-medical stuff) that I test. If that's the way to read it, picking a 135N minimum load was the right thing to do as that's way too low for a normal disk to really see except in unusual circumstances; thus the test would be conservative on that end.


On the other hand, I only glanced over the report and saw a few bone-headed mistakes that makes me wonder about the report. Fournier transform is called out in the spectroscopy section when the correct term is Fourier Transform or commonly FT by those who use it frequently. Might be a simple misspelling or it might be that the report was written by someone who's compiling data that they don't understand. If it's the latter, there might be hidden assumptions throughout that aren't necessarily the way an expert in that field might have reported it.

Thank you Anna. Good point that I hadn't considered was that the disc was always under compressive stress and just that it cycled up to 1350N at 4Hz... Which I agree would be a pretty good stress test if they did 40 million cycles.

I find it interesting that the studies on the LP-ESP state that it passes a number of biocompatibility tests.


But it also mentions that after 10 million cycles in a saline solution...



"The tests looking for salted out or released matter showed
the emission of\1 mg/kg methylene diphenyl 4-4 diisocyanate and of 64.9 mg/kg of 4-4 methylene diamine. These
results are consistent with the data in the literature "


Wikipedia suggests that MDA is a suspected carcinogen. And:


"The Occupational Safety and Health Administration has set a permissible exposure limit at 0.01 ppm over an eight-hour time-weighted average, and a short-term exposure limit at 0.10 ppm"


So to me - 64.9 mg per kg of saline... That seems like a lot.

Hey I'm getting the cp-esp as well and this is a glaring issue. I know that you've already gotten the cp-esp. May I ask why you overlooked this issue?

Sure:

1. Lesser of all evils - other discs have plastics, or just as bad maybe - nickel.
2. I take supplements already that should substantially improve my immune system
3. Won't live forever - a judgment call as to the risk of cancer versus health impact of being inactive

I looked through your posts, you make intelligent choices and arguments.

I'm about to turn 32 and require c5-7 replacement, it's causing severe canal stenosis.

Given that I will have these discs in me for another ~30-40 yrs, that'll mean exposure to the toxins released by the esp discs for similar time. I'd imagine my risk of cancer will increase due to the toxins, perhaps I should op for fusion instead. the prospect of adjacent segment disease/more fusion is more preferable to cancer/chemo.

Thank you! That is one of the few gifts I have... I'm very analytical.

I don't want to influence you either way... I will only say that I was in a similar spot, and although I'm older... I came to grips that the risk / reward was a no-brainer for me.

It took some time for me to come to that conclusion though... And it really is the "trifecta" of the items I quoted... Supplements (vitamin D among other things)... Really have been shown to have dramatic impact on various cancers.

Oh and one thing I forgot to mention... Do you realize how much plastic you're already consuming every year?

https://qz.com/1644802/you-eat-5-gra...stic-per-week/

That was the final straw for me... I just wasn't going to immobilize two vertebrae forever, causing other spine problems (I already have too many)...

Well all things considered
 

Because I am going back for a revision of my C6-7 due to HO behind my M6-C, I am hoping that Dr. Clavel will use an ESP.

I'm MUCH more confident in the LP-ESP vs the CP-ESP.

I'm reasonably astute, not a medical doctor or a prosthetic engineer... But I don't see any other device as being nearly as well designed. And while it doesn't yet have the implantations that the ProDisc or the M6 have, it does have many years of history.

The CP-ESP has a lot less... And I worry a bit about the elastomer really holding up to 30 years of life... I held a CP-ESP in my hand and it is just tiny... And the elastomer even smaller as you can tell by the imaging.

Still think the CP-ESP is probably the right one, but I'm just a lot less confident in it than I am in the LP.

Hello Jack

I am wondering what makes you confident in LP ESP?
I am concerned about life span of its silicone nucleus.
Manufacturer did some accelerated aging tests at elevated temperatures, and claims that the prosthesis will outlive the person. But I googled the info on silicone longevity and I didn’t find any silicone part that would last more than 10-20 years. Everyone knows that in old cars all rubber parts are trash in 15-20 years for sure, and especially those bushings that absorb shocks in control arms etc.
I am wondering if you considered this aspect?

Thanks