Moving the goalposts again, and also being factually wrong. Do you remember why my grandfather's hip came into the discussion? They're not. They're titanium. they're strong as fuck. But let's roll right into the riposte: WE'RE NOT METAL. At some point, the implant has to touch gooey meaty bits. Or crunchy chalky boney bits. Generally both, if you're talking a hip replacement as that shit goes into marrow. So let's review: - Leg without titanium: shortened normally - Leg with titanium: accelerated decrepitude - difference: Titanium It's pretty simple math but you keep dancing around it by pretending you don't understand. Like the paper you linked to that I can't get to that says "holy shit, no reaction in four weeks." Dude, I got milk that lasts longer than that. If your implant expires faster than dairy products it isn't applicable to the subject of transhumanism. Nobody says "I want awesome cyber shit in my body for the next couple weeks" they say "I wanna be awesomely cyber." You're essentially arguing the temporary tattoos of implantation and extrapolating out to permanence. And I'm not willing to assume you're doing it by accident. Like your canard about bacterial resistance. Once more, with feeling: an implant site is a wound, its success is directly correlated with immune response, and subverted immune response is a pathway to infection. Full stop. Our bodies will never accept implants. I've done the vivisection. I've reviewed the studies. I've been involved in the primary research. You're still going for this "fundamental advancement of medical technology" thing and ignoring the fact that human immune systems are unchanged from the time of Solomon. And the worst part is you pretend you don't even understand the evidence. Here, watch: _________________________________________________________________________ The primary failure modes for implanted shock/pace leads are related to body motion. Because the most likely site for a cardioverter is underneath the pectoralis via Superior Vena Cave (SVC) cutdown with cardiac access through the svc, leads generally travel up underneath the clavicle and back down. Rotator action (swinging the arm, either while walking or with a tennis racket, for example) provides compression upon the lead. Generalized motion causes the attitude between cardioverter and fixation site to change by a small but non-negligible amount. The FDA will sign off on any test they feel adequately reflects the failure mode of your product. In our case, our leads were made of helical small-gage MP35N, a cobalt-nickel alloy with high corrosion resistance and excellent conductivity. The coil was sheathed in implantation-grade medical tubing the composition and coatings of which were not my job; existing tests proved that their eventual breakdown by the body did not have substantially adverse effect on the charge delivered to the heart. Therefore, our primary concern was physical breakage of the coil. The first test, flexion, consisted of counter-rotating chucks each containing the end of a sample of our coil. I designed, built, tested and deployed a 3/4 HP test rig that spun 24 of these 4" samples at 10,000 RPM, like an Epilady from hell: Each rotation of the sample passed it through a complete 180 degree bend and back, without the cooling or hysteresis period that the actual lead would experience within the body. Also, atrial fibrillation patients aren't really in the habit of doing anything at 10,000 RPM so the conditions experienced by the leads were worst case, to say the least. As it is, our leads could survive approximately 18 hours of destructive testing at 10,000 RPM. Assume your patient will live 20 years. If the leads in his body somehow go through a complete 180 degree bend and back again 1500 times a day, he might need a replacement. Otherwise, he's probably good. The other test involved compression in a medium that modeled tissue. I developed a roller system and poured samples of a medical moulding compound that rolled the leads over and over again until they broke down. The tricky part was finding a molding compound that would survive long enough to cause the coils to deform. As it turns out, cobalt-nickel alloy is pretty tough. BUT NONE OF THAT SHIT MATTERED because the scar tissue that built up at the helix site rendered the leads moot after about ten years. Less, if the patient was particularly unhealthy (none of our patients were particularly healthy, much like every other implant candidate in the history of medicine). And the body could break down the sheathing and plaque up the inside of the helix and it didn't matter because it was bioinert... but the simple presence of the lead caused a substantial portion of the body's immune defenses to be redirected towards plaqueing the lead over. After five years in a sheep, what was a 1/6" diameter pace lead ended up looking like linguini. ________________________________________________________________________________________ The shit you build? Solid as fuck. That flexion tester sounded like a goddamn lear jet (I kinda fucked up the gear lash - what can I say, I was an undergrad). The body you put it in? Frail, and made out of meat. You can't fix the meat. You only think it's a bold claim because you still don't understand the problem.Hip replacements don't fail because the immune system kills them, though. They're worse at wear and tear than original bones.
Which, again, nothing to do with the implant being rejected. The bones being eroded by the metal why we have metal-on-metal hip replacements now.
Cool, how do you test that?
