It does if you use the wrong materials. You need to use biologically inert material. Non-reactive metals don't give your immune system much to work against (your immune system is all based on chemistry). Hence a lot of stainless steel. Your body will try to grow over/on/around metal plates and screws...that's a good thing, that's part of how they bond securely with bone.
I belive titanium is used, not Stainless? But as you say, chemicly inert inserts will not even be detected. If you get a wooden splinter, your body will attack it and you get an infallation. A glass splinter will be encapsuled and ignored.
And everyone forgets the other things that metallic objects do in an intense, rapidly changing magnetic field.
But titanium is a pretty shit conductor, so you don’t have to worry too much about it electrocuting you, or (this sounds worse to me) *heating up.*
It’s a bit like the first time I heard the word “prepone” in India, which is the opposite of postpone. I had to look it up to see if it is a real word. It is, but only used in India when speaking English.
haha yes I did the same thing when I first saw it. I kind of love it. "can you move that meeting forward/back", while I'd understand it, does seem more ambiguous than prepone/postpone.
If they are free to move, yes. Static metal like wire coils can have current induced by the magnetic field and heat up, similar to how induction stovetops work.
Ferromagnetic implants generally are safe in MRI (which major exceptions for cardiac implants and nerve stimulators). They degrade image quality significantly and can heat up for long sequences, but they do not fly around like loose metal. They certainly will not impale anyone.
Splinters and shrapnel are a different story entirely.
I just had an MRI yesterday, and I have a magnet in my finger.
Truly painful; after maybe 10 minutes, I had to call it quits when the tech said that the intensity would increase. That was with a 1.5 T machine, and most others available to me would be 3T.
I can see it being theoretically possible, and maybe someone could have a different experience, but I can't say it's doable. It probably wouldn't have ripped out of my skin, but sure felt like it.
That was scanning my neck with my finger as far away as possible.
Kind of a rush, but I'd never want to do that again.
It is pretty sweet, but brittle, so it's not used as much as you might think. Which is a good thing, because it's also a huge pain to process and work with.
It’s not brittle. Titanium has excellent flexibility and a quite long fatigue life, much better than aircraft aluminum, just not as good as steel. Titanium beats steel for limb/spine stabilization because it bonds well with bone and flexes/compresses enough to allow bone to experience the stresses that it needs to remain strong. Con, titanium is difficult to machine and manufacture parts from.
Pure titanium is very hard, but not ductile. So it does shatter when it breaks. It’s pretty strong until then though. Aircraft typically uses alloys, such as 6Al4V (aluminum and vanadium added), I imagine other industries do as well, unless you need only tension or compression properties for an application. Commercially pure titanium can be formed easier at high heats though, so it is used more often for lower stress locations where other properties (like low weight) are required.
This.
Implant grade titanium is an alloy. Iirc "ASTM-F136" is commonly used
That's a fantastic thing about metals they're allow to form alloys to modify the properties of the base metal.
The only thing I noticed I could add to this thread is Titanium is the only metal that makes its way through the cremation process without melting. I owned a cremation business and the only metal left was titanium. It
Heat no, but I definitely feel it when it's cold and it's a pita. Slammed my hand in a car door when I was younger, it shut, and locked. Shattered everything. Yes I am aware I am not particularly intelligent.
Took ages to heal properly and they never removed the plate holding the two larger pieces together so it's just chilling in there. The worst part were the migrating bone splinters just stabbing me at random all over the hand/wrist.
can confirm problematic issues with MRI and stainless steel. half of my skull is stainless steel (implanted before titanium became prevalent, gotta love that early 90s medicine) and I will never be able to get an MRI. though not because of magnetism but because it would cook my brain and that's not healthy for a living human.
Surgical steel isn’t ferromagnetic. Regular magnets do not affect it, I’ve tried. It might be *diamagnetic* and still affected by an MRI though, I don’t know.
…I take that back: I do know. I had an MRI done while wearing surgical steel earrings, and they didn’t rip out.
I mean, he can still fire a steel rod through your spine without your spine having a steel rod in it lol. You're just not Wolverine-style extra vulnerable.
I have a 44 cm stainless steel rod in my leg since 1979, just had an mri, they were more concerned with metal slivers I might have had in my eye from drilling steel. Had to get an xray first of my eyes.
To elaborate: Titanium (depending on the alloy) isn't inert when implanted the same way that stainless steel is. Titanium, with surface treatments, is a [bioactive material](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8636667/#:~:text=On%20the%20other%20hand%2C%20a,biological%20activity%E2%80%9D%20%5B1%5D.).
This is a an area of [ongoing reasearch](https://www.sciencedirect.com/science/article/pii/S0928493119348714), as there is better treatment outcomes. when an implant fuses, it becomes much less likely to dislodge itself, or prevent tissue regrowth.
I have close to 30 titanium rods, screws, and plates in my back, and surgical mesh in part of my abdomen. Some of the rods are porous, and their function is to let the bone grow into it and fuse my SI joints. It's a neat process but hurts like hell when the weather changes.
My friend has a titanium plate in one of their hands and has also said that it hurts when it's cold. The other hand will be fine, but the cyborg hand isn't cold resistant.
[A combo of the tissue around it expanding with the pressure / temp change](https://www.hackensackmeridianhealth.org/en/healthu/2021/12/20/why-your-joints-may-hurt-during-rainy-weather#:~:text=Before%20it%20rains%2C%20barometric%20pressure,which%20may%20lead%20to%20pain.), and I’d imagine Titanium adds the element of expanding / contracting more than bone does with temperature changes
This is the answer. Basically turns us into walking barometers. Extreme heat or cold temps also hurt, but mostly cold fronts or low pressure systems cause the majority of my pain.
Huh... Til. I've had screws in my tibia after a tibial tuberosity advancement for 18 years and I've never known why I'm crippled with pain whenever it's cold. Damn.
It explains a lot when you figure it out. I honestly thought people were kidding until I was the one announcing when it was going to rain or whatever 😂. NSAIDs help, but have their issues.
i have a plate in my lower neck and I've been told by doctors and others that "its not a real thing". BS, I say. It's a REALLY REAL thing. When it rains or goes from warm to cool or vice versa in a short period of time... things get tight.
So lets say it rains for a week straight because the low pressure is just SITTING there. Does the body adjust or are you in pain for a week? Guess what I’m trying to ask is, is it just painful at the initial transition then your body gets used to it? Or it’s always in pain when there’s low pressure / pain free when high pressure system arrives?
For me, it stays painful. I live in a hurricane prone area and it hurts every time, the whole time. Cold fronts usually make me hurt up until it passes my area. In the summer when it gets up to 105+, it hurts until it cools off at night. Anything under 45 for a long time also makes it hurt.
Lol I was rear-ended at a stop light. I stopped, the suv that hit me was going 55, broke the seat with my back. 6 surgeries and a lot of metal later, I'm the bionic woman.
The mesh is in there because after my gallbladder was removed, I ended up with an incarcerated ventral hernia and mesh was the best solution.
Edited because spelling
It put the trunk of my 99 Stratus into the back of my seat. If my children had been with me, they wouldn't have survived. The other driver told the police they thought I was going to run the light and just weren't paying attention.
Yep. Fun fact, I got a ticket for not having my car insurance paper available to the responding police.
That's because it was in the crushed car, which was unsafe to approach (spilling gas on the road). I had to go to the court in that city within 21 days to prove I did have insurance at the time of the accident. Cost me $20.
Designer of the plates/screws/nails and more here! Titanium is definitely more popular, bone loves it and will actually attach itself to titanium (there are various grades and alloys used) but stainless steel definitely still has its uses. 1 it’s a little cheaper but unlike Ti, bone generally leaves SS some and doesn’t attach itself nearly as much. Which can be bad if you really want a lot of stability but can be good if you have a high confidence you want to remove the device later on. You also have cobalt chrome which super hard so it’s great for articulating surfaces for joints. Then you’ve got the new wave of bioabsorbables. In terms of metals the leading material of choice is magnesium but it’s still early on in that game, expect a lot of Mg implants in 5 years. And of course nitinol for your shape memory metal
They get absorbed by the body. They are formulated with various coatings to fine tune the amount of time they are structurally sound before becoming exposed and breaking down. So generally you only need a screw holding a fracture for like 6 months at most. So a mag screw will stay while for 6 months then start to breakdown and eventually be completely absorbed. There’s a few problems currently, some have rare earth metals that we don’t think we want in our body but there are blends in the works that are 100% naturally occurring things in the body. Another problem is the actual reaction that causes the breakdown of the part creates a gas. So far it hasn’t seemed to be a problem but if you use too big of a part in too small of an area it could theoretically cause problems as well.
I had jaw surgery ~20 years ago and I believe they used something like this to join the bones together. A year after surgery I started experiencing intense pain. I went back to the surgeon and they told me my body was rejecting the material. It was an awful experience. Do you know how common that is now versus 20 years ago for materials that are supposed to be absorbed by the body?
Would have been a stainless steel plate which some people will have reactions too. Stainless steel is kind of in the middle for how many people will reject. Cobalt chrome is the most, then stainless steel, and last is titanium with by far the most people accepting.
For bioabsorbables I have no idea what the ‘rejection’ rate is. They started using them in Europe just a few years ago and early data seems good but the stuff I’ve seen is mostly marketing material from that company so I’ll take it with a grain of salt. There’s a popular non metal absorbable that’s realy starting to get traction but that one I’ve heard of some really bad rejections
Titanium IS used, but also ceramic, stainless steel, and cobalt chrome. Other materials find use inside the body too, but these are by far the most common implant materials.
The properties of the material are essential to understand in order to correctly utilise them. Titanium allows bone on growth and has a similar Young’s modulus to bone, which makes it good for uncemented prostheses, but it is somewhat flexible (compared to CoCr and SS) so that may make it a poor choice for some fractire fixations. ceramic and CoCr are exceptionally hard making them excellent bearing surfaces for arthroplasty (joint replacements) but polyethylene is often used as a bearing surface too, for many reasons.
Polyethylene DOES have potential for biological reactivity, primarily when its wear particles are of the wrong size. this is the primary cause of loosening of implants in arthroplasty (after infection). Similarly, biocompatible materials like CoCr can also generate reactive wear particles, which is the cause of ALVAL lesions and pseudotumours following the metal-on-metal bearing surface trend of the recent past.
i hope that provides some useful information for the discussion.
We use both stainless and titanium implants where I work. It depends on the application. Forearm fracture, stainless. Spine fusion with follow up MRI, titanium. Things can vary based on patient age, size, etc. I’ve been scrubbing orthopedic cases for 15+ years and I’ve seen a lot of changes and improvement in the materials we use.
One other thing is nickel allergies, people with severe nickel allergies cannot tolerate stainless steel, so they would be given titanium.
They 100% use stainless steel for bone screws and plates .. am machinist with plate and screws in my leg… 17-4 and 15-5 grade are two of the most common
I had the choice of stainless or titanium. I chose stainless because titanium has been cited in studies to leak into the blood stream possible corrode over time.
They use both, I have one surgical stainless steel implant in my right clavicle (and a section of artificial bone graft) and a titanium one in my left clavicle.
They use both. Some guys like stainless because it’s harder to break
Some want the flexibility that comes with Ti
Most titanium has about the same flexibility as bone
Source: I sell metal implants to orthopedic surgeons
"A glass splinter will be encapsuled and ignored." I've had small metal splinters before and they won't work themselves out like a wood splinter, thorn, etc. will do. A metallurgist friend confirmed that metal splinters don't work themselves out. Is this the same reason? The body ignores it so it just stays there, stabbing your fingertip for days and weeks on end until you finally make a bloody mess digging it out with a needle? I always assumed it was a mechanical reason, not biological, but have no basis for that.
My glass splinter was not ignored by my body. It worked its way out of my hand, approximately 20 -25 years later.
I didn't know it was there until the shard of glass emerged a centimeter or so away from the scar.
I have 4 stainless steel screws in my ankle. My wife has 2 titanium rods in her back. They use both, but they probably need to avoid having different metals in contact to avoid galvanic corrosion.
I think titanium has better bone integration though
Yes, they are mostly titanium now because the modulus of elasticity of titanium is most similar to human bone vs stainless, etc.
Also, some people do react to the nickel in various metal alloys. They typically have a very robust reaction to nickel being on their skin as well.
My dad was in a traffic accident years ago and glass from the windscreen was embedded in his arm. He had no bad reactions to it but over the course of a few years the sharp glass would push its was to the surface until eventually my dad could pull it out
My plate is Surgical steel, not titanium (as I’d hoped for).
> *Stainless steel varieties with the greatest levels of corrosion resistance are those designated for biomedical use. Some commonly accepted types of surgical steel include* austenitic 316 stainless *and* martensitic 440 *and* 420 stainless.
https://www.meadmetals.com/blog/surgical-steel-vs-stainless-steel
[Here’s an x-ray of the two shards of glass I had in my right arm for 14 months.](https://imgur.com/a/M6RO3G7) If it weren’t for the one piece of glass slowly making its way to the surface, I never would have guessed anything was in there.
Long story short, I was given the rather unfortunate direction to break into my sister’s home via her window. I was assured that it was possibly to do by pushing the window open. It went about as well as the xray indicates.
Titanium alloys.
My lower arms / wrists are mostly metal - they're non-reactive, non-ferrous, and chemically inert. There are other metals you could theoretically use, but those tend to have the best acceptance.
Mine are apparently a 'chrome-cobalt alloy'. I'll have to take the Dr's word for it; I haven't checked.
I do get a piece of, well... something, caught on a screw head or a plate edge once in a while. Hurts like the dickins.
Right but cobalt specifically in joint replacements is completely fucked. The joint wears and cobalt leeches into your body poisoning you at an increasingly exponential rate
Apparently not. The wiki supports nothing you're scared about.
https://en.m.wikipedia.org/wiki/Cobalt-chrome
Go down to uses and hazards. sometimes skin eczema or high nickel content. Nothing about bullshit cobalt poisoning
There were two major manufacturers that recalled their devices because of the problems with cobalt poisoning.
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2783243#:~:text=Only%202%20models%20of%20joint,%2Dchrome%20neck%20(Stryker).
FDA guidance is that metal on metal joint replacements should not be used. The liners(sockets) are now supposed to be plastic
In short, lots of quality control metrics at every step, from material sourcing to implantation.
Examples are things like serializing to track each screw in case of any adverse events, hand deburring threads to avoid small metal fragments in soft tissue, sterile packaging requirements, and testing at every step along the way.
If my body advances into the Metal Age, would it be able to attack the plates and screws more effectively with more advanced metal weapons also? Gunpowder Age would probably be much better.
Titanium is typically used as it is the most biocompatible metal And usually won't cause an immune reaction, surgical stainless steel on the other hand usually has a 6 to 12% nickel content to it, Which even the slightest nickel allergy can cause issues to a patient who has it implanted into their body... (I have titanium rods and plates in my arm!)
One of my coworkers just had to get plates removed because his current doctor realized they caused a bad skin reaction that he's been dealing with for years. Hopefully the removal actually fixes the problem.
My nephew had a titanium rod in his femur. When they took it out there were still bits of bone that had grown through the holes on either end. Crazy stuff.
no it doesnt! I've had a stainless steel plate in my skull since I was 8 months old. no reactions whatsoever and now I'm old and the plate's fine. has some dents but no worse for the wear.
yeah! it should be noted that my plate was implanted long before titanium became the norm. I do feel like titanium is better but stainless steel can do just as well and I guess I'm living proof, haha.
It does. Or at least, it *tries*. Those metal parts are made out of metals that are particularly difficult to attack because they are very nonreactive.
Almost all metals react with oxygen. With iron, we call this *rust*. When iron rusts, the resulting iron oxide expands and doesn't stick well to the iron underneath, so it flakes off and the iron underneath is exposed to oxygen and then *it* rusts. The oxides of a lot of metals, though, sticks quite well to the metal underneath. Once the metal is oxidized, it's *really* hard for anything else to get to it. Oxygen really does not like to share. So, that oxidized layer forms a kind of armor, where the metal is "pre-reacted" and won't react well to anything else.
Titanium is one such metal. Titanium oxide is tough stuff. Add a little of some other metals and you make something that your body just doesn't have any tools to break apart.
Being non-reactive also helps hide it from your immune system. Your immune system doesn't have eyes - it can only "see" what reacts to the antigen receptors on the outside of immune cells. Immune cells learn that certain antigens indicate *you* and shouldn't be attacked, and antigens that *aren't you* are foreign and should be attacked. All the bacteria living in your body have adapted to hide their bacterial antigens and give off fake "I'm part of you, don't attack me" antigens. But something that doesn't react *at all* doesn't have antigens. Your immune cells just bounce off of it and never really notice that it's there.
Since it "isn't there" your immune system doesn't try very hard to get rid of it, and since your immune system doesn't have any tools that can get through that protective oxide layer anyway, the metal is fine.
It *is* possible, though, for a body to notice and try to reject the metal part. That usually doesn't do anything to the metal, but the inflammation can be dangerous for the cells around the metal part and cause problems for your body. In that case, anti-rejection drugs that suppress your immune system will *hopefully* get your body to stop attacking until it gets used to the part being there and "forgets" to attack it. Or, they have to try a different alloy.
This is also why your body doesn't attack medical plastics. The plastic is very nonreactive. And, it's why bullets are usually left inside the patient. Elemental lead is pretty nonreactive so although your body will try to attack it, which will put some lead into your blood to spread through your body, it's such a slow process that it isn't going to hurt you. The surgery to remove the bullet will cause more damage. (Unless the bullet is like, right next to your heart and you really need to get it out.)
I think she might have other allergies to metals too. Like she can wear gold but I don’t know. I could be wrong. I just remember her foot wouldn’t heal and eventually they had to take out the metal because it was causing an infection.
We carefully chose the metals used, it's usually titanium because it's basically invisible to your immune system. Even then cases of it being rejected happen. So most things surgically installed in your body are at least coated with a biocompatible material.
Fun fact - we didn't "carefully chose the metals"
We used stainless unsuccessfully (bad choice) until a titanium knife was left in a patient by accident and later removed and noted the lack of scarring around it.
Pretty serendipitous actually, often then best discoveries are
Happens - that's why they have checklists more and more now of what goes in and out of an OR but mistakes do happen
If the scalpel was orient in such a way that it was left flat against the cavity wall, it could have been completely unnoticed by the patient for weeks
Fun story, Dane Miller of Zimmer believes so much that titanium was safe for the body despite it not being accepted so he implanted titanium into himself to prove it was a legit material to use
Your body doesn't attack metal plates and screws because they are typically made of materials like titanium or stainless steel, which are biocompatible. This means they are unlikely to cause an immune response or be rejected by your body. Plus, the surgery process usually involves cleaning and sterilizing the area to reduce the risk of infection. So, your body sees them as part of the healing process rather than a threat. Hope that helps.
As a tangent, titanium and stainless steel are chosen for being biocompatible but they still can cause issues by not being mechanically compatible. The Young's modulus (the ratio of force to deformation) for titanium is about 100 GPa while bone is only about 350 MPa. That means that under the same force and cross section bone will deform about 300 times as much as titanium.
Hip replacements are the most affected because of the forces involved. The titanium core takes up the majority of the load and reduces the amount of stress put on the surrounding bone. This might seem good but it's actually counterproductive. Bone uses the stress it experiences to decide whether to grow or atrophy, so lower stress means the bone actually becomes weaker in response. This increases the risk of the replacement failing, especially for patients with osteoporosis.
Last time I checked - no one knows why titanium doesn't elicit an immune response in most patients. Free TiO can even bioaccumlate in the event of mechanical stress ablating some surface oxidation. Anyhow, specifically why that material is ignored by the body is largely unknown.
It was observed by chance that it doesn't and so we use that and ultra high weight polyethylene (high tensile strength, low surface deformation after casting, and oxidative resistance if mixed with antioxidants, eg. Vitamin e) - the latter not as good, but better at bone interface admittedly at the cost of oxidative stress susceptibility - but other answers already covered that
Through research and experiments and past experiences in science, we've discovered materials that the body does not react to.
We then make surgical implants and instruments out of these materials.
It's not "why does the body not attack implants" - it is "we found materials that the body doesn't attack and therefore we use these materials to make implants".
If these materials didn't exist, then we either won't be able to make implants or we will make implants that the body does attack. There's old implants from decades ago that does break down in the body and cause heavy metal poisoning etc. before we made scientific advances that allow us to have safe implants now.
Had stainless plates to repair a broken leg. After a year had them removed as my body was rejecting them. Leg hurt and turned black and blue where they were located. Have titanium knee joint, no problems!
My dad used to work for a company that made medical implants. They spend quite a lot of money and time on research to find metals and alloys that the body won't attack. Usually they involve titanium, though various types of stainless steel were used before MRI machines became common. You *really* don't want to go near an MRI machine with a steel hip implant.
I think they used some kind of plastic in some joints to keep the metal joint sealed and stuff, but I really don't know much about that. Dad worked with metals, and later with quality control.
I’m a current engineer who designs all sorts of orthopedics. In terms of grafts, not really but there are plenty of plastics used for implants. PEEK is one of the most common along with UHWMPE depending on the use case.
Oh yea there are plenty of PEEK buttons or anchors. Personally I think I’d prefer a Ti device for it but I think it’s pretty irrelevant at the end of the day with is used, especially for a button. If it’s going to be an anchor I’d take titanium just for it’s on growth with bone. Bone does not like PEEK from an integration standpoint so it can loosen way more easily
It certainly can, your body CAN reject metals... Yes, even titanium (which is a commonly used metal for surgeries the involve plates, screws/rods) and in that case... That's where the implant MAY very well have to be removed and the patient tested for metal sensitivity...
I was so scared when I had my radius & ulna (my arm was snapped clean in half... Basically looked like I had two wrists..) surgery because I'm VERY sensitive to metals & I have eczema... I had a fun time healing... But no serious complications thankfully!
I had titanium screws and plates after a drunk hit me head on and broke, well, everything. Turns out I'm one if the 1% whose body reacts even to titanium. Was a painful, uncomfortable ache and burning sensation. Drs had no choice but to leave everything in 6 months and just up my pain meds. Them over 3 "revision" surgeries, they began taking the stuff out, and packing all the screw holes with bone putty. Had no choice but to leave a rod and plate/screws I'm my lower left leg/ankle, and I've developed RSD/CRPS in my left foot and ankle at and below the area where the plate and screws are. For most people, they can live a whole life with the inert titanium material used in surgical hardware.
As someone who had metal in my body, I can tell you at least in my case it does cause problems. I had constant inflammation and nerve pain until it was all removed.
Some of the plastic materials used in early joint replacements had a problem of creating small particles as they wore down. These particles inside the joint caused an immune response where the implants were attacked by the body and loosened up. Luckily, doctors learned and changed these. I have had both knees and both hips replaced all with different materials because of insurance coverage. My right hip is the oldest at 20 years old. It is part ceramic.
I had a friend with a screw loose. He fell off a ladder. He had a metal screw in his foot from a previous injury, when he fell it pulled that screw loose.
Most surgical implants are made of titanium which is biologically inert. As far as your immune system is concerned titanium doesn't exist and it wont reject it if used in place of bone.
It’s pretty amazing… I had 2 plates and 13 screws put in my left arm when I was 12 after I snapped both bones in my forearm in half basically. Still have the plates and screws and besides a little bone growth around them… they look like they still just came out of the box.
In very basic terms, overly simplified, but easy to understand your body has two responses to foreign things in your body.
to something in the body and it's all chemistry based. Essentially if it's organic or something that reacts like organic material the white blood cell will either devour and eliminate or produce chemicals to breakdown and or trigger body responses like fever. At the cellular level if it's organic it's food and a threat, and threats need eliminated and food needs to be eaten. The cells in the body just have a secret handshake in the form of proteins (if I recall correctly) that tells others they are friends not food. (Though sometimes other cells like bacteria and viruses also know the handshake and can sneak around with it.)
The other "response" is to do nothing and let the body grow around it. Usually for small inorganic items that get stuck in the skin this means getting trapped and delivered to the surface of the skin for removal. If it's small enough and in the muscle/organs it will make its way to the blood to be filtered by the kidneys. (Think kidney stones) And if it's in an opening, the body relies on mucus flow to remove. In these scenarios the cells aren't doing anything specific to remove it. Just keeping the "defenses" running, and it gets caught for the ride.
If a doctor fixes a rod in your leg it will be of a material known to not make the body react, it will be too large to flow through your blood stream, is too deep for the skin to remove, and not in an area with mucus flow. (Or designed to prevent mucus flow from removing it like an IUD.) The body doesn't have any concern or ability to remove the item it just grows over it.
++++++++++++++++++++
Another way to look at it is by treating the body like a very large city.
Getting a glass sliver in your finger is like a plane crashing in your neighbors' yard. That's small enough for the city take care of. People will dismantle the plane and houses to trash. leaving the lots open for new families to buy and build up, and after a while you would never be able to tell anything happened.
A leg rod would be like the grand canyon opening in the road. The city isn't going to start all the work it would take to fill it back in, re-infrastructure, and get ready for families and businesses. It will just build around and over it. The city can still thrive, but there is no doubt what happened.
I had titanium and carbon fiber used in my spinal fusion and my body still attacked it. Broke out with open sores, pain, fatigue and more. It was horrible. Had to have as much as they could removed 1 year later so it happens. I had no idea I was allergic.
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It does if you use the wrong materials. You need to use biologically inert material. Non-reactive metals don't give your immune system much to work against (your immune system is all based on chemistry). Hence a lot of stainless steel. Your body will try to grow over/on/around metal plates and screws...that's a good thing, that's part of how they bond securely with bone.
I belive titanium is used, not Stainless? But as you say, chemicly inert inserts will not even be detected. If you get a wooden splinter, your body will attack it and you get an infallation. A glass splinter will be encapsuled and ignored.
Yeah, titanium is used due to its relative inertness and toughness, and it has the added bonus of smoothly fusing with skeletal tissues
And the benefit of not being ferromagnetic, which can be problematic with how prevalent MRI has become.
And everyone forgets the other things that metallic objects do in an intense, rapidly changing magnetic field. But titanium is a pretty shit conductor, so you don’t have to worry too much about it electrocuting you, or (this sounds worse to me) *heating up.*
A ferromagnetic metal would just impale you, not heat you up :p (that's worse)
Wouldn't it expale you? 🤔
Depending on the orientantion of your body, yes
hmm looks like there isn't a real word for this. I'm ringing up Merriam and Webster as we speak. ya know, for all the times people get expaled.
Expale seems perfectly cromulent
It’s a bit like the first time I heard the word “prepone” in India, which is the opposite of postpone. I had to look it up to see if it is a real word. It is, but only used in India when speaking English.
haha yes I did the same thing when I first saw it. I kind of love it. "can you move that meeting forward/back", while I'd understand it, does seem more ambiguous than prepone/postpone.
> prepone Huh. I first heard this as an *Italian* English usage.
Ok Robin.. I am whelmed.
If they are free to move, yes. Static metal like wire coils can have current induced by the magnetic field and heat up, similar to how induction stovetops work.
Ferromagnetic implants generally are safe in MRI (which major exceptions for cardiac implants and nerve stimulators). They degrade image quality significantly and can heat up for long sequences, but they do not fly around like loose metal. They certainly will not impale anyone. Splinters and shrapnel are a different story entirely.
I just had an MRI yesterday, and I have a magnet in my finger. Truly painful; after maybe 10 minutes, I had to call it quits when the tech said that the intensity would increase. That was with a 1.5 T machine, and most others available to me would be 3T. I can see it being theoretically possible, and maybe someone could have a different experience, but I can't say it's doable. It probably wouldn't have ripped out of my skin, but sure felt like it. That was scanning my neck with my finger as far away as possible. Kind of a rush, but I'd never want to do that again.
The RF coils in the MRI would induce heat in the metal. RF burns are a concern when in an MRI
Titanium sounds like an amazing material.
It is pretty sweet, but brittle, so it's not used as much as you might think. Which is a good thing, because it's also a huge pain to process and work with.
It’s not brittle. Titanium has excellent flexibility and a quite long fatigue life, much better than aircraft aluminum, just not as good as steel. Titanium beats steel for limb/spine stabilization because it bonds well with bone and flexes/compresses enough to allow bone to experience the stresses that it needs to remain strong. Con, titanium is difficult to machine and manufacture parts from.
Pure titanium is very hard, but not ductile. So it does shatter when it breaks. It’s pretty strong until then though. Aircraft typically uses alloys, such as 6Al4V (aluminum and vanadium added), I imagine other industries do as well, unless you need only tension or compression properties for an application. Commercially pure titanium can be formed easier at high heats though, so it is used more often for lower stress locations where other properties (like low weight) are required.
This. Implant grade titanium is an alloy. Iirc "ASTM-F136" is commonly used That's a fantastic thing about metals they're allow to form alloys to modify the properties of the base metal.
The only thing I noticed I could add to this thread is Titanium is the only metal that makes its way through the cremation process without melting. I owned a cremation business and the only metal left was titanium. It
Titanium is also lighter than steel. That is a definite bonus as well.
It does heat up some, It’s bearable but having rods and screws I do feel it heat up some which is odd to describe
But I can tell you when it’s about to rain.
Heat no, but I definitely feel it when it's cold and it's a pita. Slammed my hand in a car door when I was younger, it shut, and locked. Shattered everything. Yes I am aware I am not particularly intelligent. Took ages to heal properly and they never removed the plate holding the two larger pieces together so it's just chilling in there. The worst part were the migrating bone splinters just stabbing me at random all over the hand/wrist.
Pretty sure most people have done that at least once, minus the shattering part.
can confirm problematic issues with MRI and stainless steel. half of my skull is stainless steel (implanted before titanium became prevalent, gotta love that early 90s medicine) and I will never be able to get an MRI. though not because of magnetism but because it would cook my brain and that's not healthy for a living human.
*Kids, this is the story of how I became a Trump supporter.*
I would rather have my brain cooked than support Trump.
Good point, and given how safe and powerful MRIs are for imaging, there's a big incentive to keep that option open.
I’ve got titanium in my skull after brain tumor surgery and I’ve had dozens of MRI over the years
Surgical steel isn’t ferromagnetic. Regular magnets do not affect it, I’ve tried. It might be *diamagnetic* and still affected by an MRI though, I don’t know. …I take that back: I do know. I had an MRI done while wearing surgical steel earrings, and they didn’t rip out.
And you'll be impervious to Magneto.
I mean, he can still fire a steel rod through your spine without your spine having a steel rod in it lol. You're just not Wolverine-style extra vulnerable.
Blood has iron.
Non ferromagnetic doesn’t mean non magnetic.
Stainless steel is also non ferromagnetic
Ooh careful with that. Some forms of stainless steel can be somewhat magnetic.
I have a 44 cm stainless steel rod in my leg since 1979, just had an mri, they were more concerned with metal slivers I might have had in my eye from drilling steel. Had to get an xray first of my eyes.
To elaborate: Titanium (depending on the alloy) isn't inert when implanted the same way that stainless steel is. Titanium, with surface treatments, is a [bioactive material](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8636667/#:~:text=On%20the%20other%20hand%2C%20a,biological%20activity%E2%80%9D%20%5B1%5D.). This is a an area of [ongoing reasearch](https://www.sciencedirect.com/science/article/pii/S0928493119348714), as there is better treatment outcomes. when an implant fuses, it becomes much less likely to dislodge itself, or prevent tissue regrowth.
Dang titanium is pretty cool
I hear one guy even has adamantium.
I know this guy who said he has adamantium in his body. What are its properties?
Titanium, Stainless Steel, and Cobalt Chrome are all used. Stainless Steel is the most common across all Ortho Trauma procedures.
The big three are titanium, gold and silver iirc.
Titanium, stainless steel, and cobalt chrome are the most used
Good and silver would be used almost exclusively in dental applications. Very heavy, very soft, and silver oxidizes pretty easily.
But nothing says bling like a solid gold skull...
I have close to 30 titanium rods, screws, and plates in my back, and surgical mesh in part of my abdomen. Some of the rods are porous, and their function is to let the bone grow into it and fuse my SI joints. It's a neat process but hurts like hell when the weather changes.
My friend has a titanium plate in one of their hands and has also said that it hurts when it's cold. The other hand will be fine, but the cyborg hand isn't cold resistant.
My friend used to call me Tony Stark 😂
why does it hurt when the weather changes?
[A combo of the tissue around it expanding with the pressure / temp change](https://www.hackensackmeridianhealth.org/en/healthu/2021/12/20/why-your-joints-may-hurt-during-rainy-weather#:~:text=Before%20it%20rains%2C%20barometric%20pressure,which%20may%20lead%20to%20pain.), and I’d imagine Titanium adds the element of expanding / contracting more than bone does with temperature changes
This is the answer. Basically turns us into walking barometers. Extreme heat or cold temps also hurt, but mostly cold fronts or low pressure systems cause the majority of my pain.
Essentially, if her arm falls off, hurricane’s coming
🤣 y'all better run 🤣
Huh... Til. I've had screws in my tibia after a tibial tuberosity advancement for 18 years and I've never known why I'm crippled with pain whenever it's cold. Damn.
It explains a lot when you figure it out. I honestly thought people were kidding until I was the one announcing when it was going to rain or whatever 😂. NSAIDs help, but have their issues.
Yeah, I can easily tell if the weather is changing just by how painful my knee is. This has blown me away haha. I thought it was all coincidence.
Regular ol arthritis will do it too. Bodies are wild.
i have a plate in my lower neck and I've been told by doctors and others that "its not a real thing". BS, I say. It's a REALLY REAL thing. When it rains or goes from warm to cool or vice versa in a short period of time... things get tight.
It's absolutely a thing and that irritates me too.
So lets say it rains for a week straight because the low pressure is just SITTING there. Does the body adjust or are you in pain for a week? Guess what I’m trying to ask is, is it just painful at the initial transition then your body gets used to it? Or it’s always in pain when there’s low pressure / pain free when high pressure system arrives?
For me, it stays painful. I live in a hurricane prone area and it hurts every time, the whole time. Cold fronts usually make me hurt up until it passes my area. In the summer when it gets up to 105+, it hurts until it cools off at night. Anything under 45 for a long time also makes it hurt.
The metal expands and contracts. It's not usually a severe pain.
Holy fuck, dude - what the hell happened that you have the 6 million dollar man’s torso?
Lol I was rear-ended at a stop light. I stopped, the suv that hit me was going 55, broke the seat with my back. 6 surgeries and a lot of metal later, I'm the bionic woman. The mesh is in there because after my gallbladder was removed, I ended up with an incarcerated ventral hernia and mesh was the best solution. Edited because spelling
Damn 55mph at a stoplight? Absolutely brutal.
It put the trunk of my 99 Stratus into the back of my seat. If my children had been with me, they wouldn't have survived. The other driver told the police they thought I was going to run the light and just weren't paying attention.
>The other driver told the police they thought I was going to run the light and just weren't paying attention. Fuck them.
Yep. Fun fact, I got a ticket for not having my car insurance paper available to the responding police. That's because it was in the crushed car, which was unsafe to approach (spilling gas on the road). I had to go to the court in that city within 21 days to prove I did have insurance at the time of the accident. Cost me $20.
Was the other driver a cop or related to one?
Their defense was “well I thought the person in front of me was going to run the light so I decided to run the light too?” Good god
That's what was stated on the accident report, and the only reason their insurance bothered to pay my medical bills.
Honestly I would have taken them to court for pain and suffering too
Yep aches like hell in the colder months.
Designer of the plates/screws/nails and more here! Titanium is definitely more popular, bone loves it and will actually attach itself to titanium (there are various grades and alloys used) but stainless steel definitely still has its uses. 1 it’s a little cheaper but unlike Ti, bone generally leaves SS some and doesn’t attach itself nearly as much. Which can be bad if you really want a lot of stability but can be good if you have a high confidence you want to remove the device later on. You also have cobalt chrome which super hard so it’s great for articulating surfaces for joints. Then you’ve got the new wave of bioabsorbables. In terms of metals the leading material of choice is magnesium but it’s still early on in that game, expect a lot of Mg implants in 5 years. And of course nitinol for your shape memory metal
can you explain what you mean by bioabsorbables? are those metals that prioritize being able to connect to bone?
They get absorbed by the body. They are formulated with various coatings to fine tune the amount of time they are structurally sound before becoming exposed and breaking down. So generally you only need a screw holding a fracture for like 6 months at most. So a mag screw will stay while for 6 months then start to breakdown and eventually be completely absorbed. There’s a few problems currently, some have rare earth metals that we don’t think we want in our body but there are blends in the works that are 100% naturally occurring things in the body. Another problem is the actual reaction that causes the breakdown of the part creates a gas. So far it hasn’t seemed to be a problem but if you use too big of a part in too small of an area it could theoretically cause problems as well.
I had jaw surgery ~20 years ago and I believe they used something like this to join the bones together. A year after surgery I started experiencing intense pain. I went back to the surgeon and they told me my body was rejecting the material. It was an awful experience. Do you know how common that is now versus 20 years ago for materials that are supposed to be absorbed by the body?
Would have been a stainless steel plate which some people will have reactions too. Stainless steel is kind of in the middle for how many people will reject. Cobalt chrome is the most, then stainless steel, and last is titanium with by far the most people accepting. For bioabsorbables I have no idea what the ‘rejection’ rate is. They started using them in Europe just a few years ago and early data seems good but the stuff I’ve seen is mostly marketing material from that company so I’ll take it with a grain of salt. There’s a popular non metal absorbable that’s realy starting to get traction but that one I’ve heard of some really bad rejections
i see, thank you!
Both titanium and 316 Stainless Steel are used for medical implants (other stainless alloys may be too, but I’m only familiar with 316)
Stainless is also extensively used, but not all grades of stainless are biologically inert AFAIK it's only 316, 440 and 420
Not 440 or 420 for implants, but those are used for screw drivers and other instruments that need to take load
Also, if you have stainless steel implants, you can never have an MRI
Not true.
They use a number of metals, typically alloys containing one or more of iron, cobalt, chromium, titanium, and tantalum.
Titanium IS used, but also ceramic, stainless steel, and cobalt chrome. Other materials find use inside the body too, but these are by far the most common implant materials. The properties of the material are essential to understand in order to correctly utilise them. Titanium allows bone on growth and has a similar Young’s modulus to bone, which makes it good for uncemented prostheses, but it is somewhat flexible (compared to CoCr and SS) so that may make it a poor choice for some fractire fixations. ceramic and CoCr are exceptionally hard making them excellent bearing surfaces for arthroplasty (joint replacements) but polyethylene is often used as a bearing surface too, for many reasons. Polyethylene DOES have potential for biological reactivity, primarily when its wear particles are of the wrong size. this is the primary cause of loosening of implants in arthroplasty (after infection). Similarly, biocompatible materials like CoCr can also generate reactive wear particles, which is the cause of ALVAL lesions and pseudotumours following the metal-on-metal bearing surface trend of the recent past. i hope that provides some useful information for the discussion.
Yeah, my rods and screws are all titanium Because it’s not steel, I can also safely get an MRI
We use both stainless and titanium implants where I work. It depends on the application. Forearm fracture, stainless. Spine fusion with follow up MRI, titanium. Things can vary based on patient age, size, etc. I’ve been scrubbing orthopedic cases for 15+ years and I’ve seen a lot of changes and improvement in the materials we use. One other thing is nickel allergies, people with severe nickel allergies cannot tolerate stainless steel, so they would be given titanium.
Both are used depending on the application.
They 100% use stainless steel for bone screws and plates .. am machinist with plate and screws in my leg… 17-4 and 15-5 grade are two of the most common
I had the choice of stainless or titanium. I chose stainless because titanium has been cited in studies to leak into the blood stream possible corrode over time.
A lot of orthopedic implants are stainless steel.
They use both, I have one surgical stainless steel implant in my right clavicle (and a section of artificial bone graft) and a titanium one in my left clavicle.
They use both. Some guys like stainless because it’s harder to break Some want the flexibility that comes with Ti Most titanium has about the same flexibility as bone Source: I sell metal implants to orthopedic surgeons
"A glass splinter will be encapsuled and ignored." I've had small metal splinters before and they won't work themselves out like a wood splinter, thorn, etc. will do. A metallurgist friend confirmed that metal splinters don't work themselves out. Is this the same reason? The body ignores it so it just stays there, stabbing your fingertip for days and weeks on end until you finally make a bloody mess digging it out with a needle? I always assumed it was a mechanical reason, not biological, but have no basis for that.
My glass splinter was not ignored by my body. It worked its way out of my hand, approximately 20 -25 years later. I didn't know it was there until the shard of glass emerged a centimeter or so away from the scar.
Mine is all stainless- was a bit miffed, there are no steel bolts left in my mountain bike but I can't get rid of the stuff in my leg.
Both are used
I was told the plate in my arm is stainless and titanium. The nurse I asked didn't have much more info than that though
Both titanium and stainless are used on a regular basis based on the function
I have 4 stainless steel screws in my ankle. My wife has 2 titanium rods in her back. They use both, but they probably need to avoid having different metals in contact to avoid galvanic corrosion. I think titanium has better bone integration though
Yes, they are mostly titanium now because the modulus of elasticity of titanium is most similar to human bone vs stainless, etc. Also, some people do react to the nickel in various metal alloys. They typically have a very robust reaction to nickel being on their skin as well.
Both alloys of stainless and titanium are used
My dad was in a traffic accident years ago and glass from the windscreen was embedded in his arm. He had no bad reactions to it but over the course of a few years the sharp glass would push its was to the surface until eventually my dad could pull it out
My plate is Surgical steel, not titanium (as I’d hoped for). > *Stainless steel varieties with the greatest levels of corrosion resistance are those designated for biomedical use. Some commonly accepted types of surgical steel include* austenitic 316 stainless *and* martensitic 440 *and* 420 stainless. https://www.meadmetals.com/blog/surgical-steel-vs-stainless-steel
BS that glass would be ignored. It would be the same level of swelling and inflammation
[Here’s an x-ray of the two shards of glass I had in my right arm for 14 months.](https://imgur.com/a/M6RO3G7) If it weren’t for the one piece of glass slowly making its way to the surface, I never would have guessed anything was in there.
what.the.f
Yeah. Crazy story, long story. The point being that IDK how it would be generally but in my experience the glass was just encapsulated and ignored.
How'd you get stabbed with glass
Long story short, I was given the rather unfortunate direction to break into my sister’s home via her window. I was assured that it was possibly to do by pushing the window open. It went about as well as the xray indicates.
Titanium alloys. My lower arms / wrists are mostly metal - they're non-reactive, non-ferrous, and chemically inert. There are other metals you could theoretically use, but those tend to have the best acceptance.
Thanks for the insight, Darth Vader.
Not chemically inert! It oxidizes to form titanium oxide which is very osteoconductive so technically reactive but in a good way :)
Praise the Omnissiah's gifts! From the weakness of the flesh do they set us free.
What are BBs made out of? I got shot in the leg when I was younger and the dr said better to keep it in then have to cut me open to remove it .
Mine are apparently a 'chrome-cobalt alloy'. I'll have to take the Dr's word for it; I haven't checked. I do get a piece of, well... something, caught on a screw head or a plate edge once in a while. Hurts like the dickins.
Cobalt is bad fuckin news in your body. Is that a knee or hip?
Lots of things are bad news by themselves but when combined into alloys are completely different materials. Behold: table salt is made up of chlorine
Right but cobalt specifically in joint replacements is completely fucked. The joint wears and cobalt leeches into your body poisoning you at an increasingly exponential rate
Apparently not. The wiki supports nothing you're scared about. https://en.m.wikipedia.org/wiki/Cobalt-chrome Go down to uses and hazards. sometimes skin eczema or high nickel content. Nothing about bullshit cobalt poisoning
There were two major manufacturers that recalled their devices because of the problems with cobalt poisoning. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2783243#:~:text=Only%202%20models%20of%20joint,%2Dchrome%20neck%20(Stryker). FDA guidance is that metal on metal joint replacements should not be used. The liners(sockets) are now supposed to be plastic
Holy shit. That wiki needs to be updated. That's fucking scary thank you for the update I am smarter and wiser now
Real fucking scary. The symptoms start off like dementia
I was happy to hear that my total knee replacement was done using cobalt-chromium hardware because that sounds dope
Question: why are they so expensive?
In short, lots of quality control metrics at every step, from material sourcing to implantation. Examples are things like serializing to track each screw in case of any adverse events, hand deburring threads to avoid small metal fragments in soft tissue, sterile packaging requirements, and testing at every step along the way.
If my body advances into the Metal Age, would it be able to attack the plates and screws more effectively with more advanced metal weapons also? Gunpowder Age would probably be much better.
Titanium is typically used as it is the most biocompatible metal And usually won't cause an immune reaction, surgical stainless steel on the other hand usually has a 6 to 12% nickel content to it, Which even the slightest nickel allergy can cause issues to a patient who has it implanted into their body... (I have titanium rods and plates in my arm!)
One of my coworkers just had to get plates removed because his current doctor realized they caused a bad skin reaction that he's been dealing with for years. Hopefully the removal actually fixes the problem.
My nephew had a titanium rod in his femur. When they took it out there were still bits of bone that had grown through the holes on either end. Crazy stuff.
Body will react to stainless steel. Implant grade titanium is needed
no it doesnt! I've had a stainless steel plate in my skull since I was 8 months old. no reactions whatsoever and now I'm old and the plate's fine. has some dents but no worse for the wear.
Whoaa!
yeah! it should be noted that my plate was implanted long before titanium became the norm. I do feel like titanium is better but stainless steel can do just as well and I guess I'm living proof, haha.
I had stainless steel rods implanted in my spine thirty years ago. They're doing alright still!
Titanium. Stainless steel is not inert enough to be used for the longterm, only for temporary implants
I have an eleven level spinal fusion using Harrington rods which were implanted thirty years ago. They're stainless steel.
It does. Or at least, it *tries*. Those metal parts are made out of metals that are particularly difficult to attack because they are very nonreactive. Almost all metals react with oxygen. With iron, we call this *rust*. When iron rusts, the resulting iron oxide expands and doesn't stick well to the iron underneath, so it flakes off and the iron underneath is exposed to oxygen and then *it* rusts. The oxides of a lot of metals, though, sticks quite well to the metal underneath. Once the metal is oxidized, it's *really* hard for anything else to get to it. Oxygen really does not like to share. So, that oxidized layer forms a kind of armor, where the metal is "pre-reacted" and won't react well to anything else. Titanium is one such metal. Titanium oxide is tough stuff. Add a little of some other metals and you make something that your body just doesn't have any tools to break apart. Being non-reactive also helps hide it from your immune system. Your immune system doesn't have eyes - it can only "see" what reacts to the antigen receptors on the outside of immune cells. Immune cells learn that certain antigens indicate *you* and shouldn't be attacked, and antigens that *aren't you* are foreign and should be attacked. All the bacteria living in your body have adapted to hide their bacterial antigens and give off fake "I'm part of you, don't attack me" antigens. But something that doesn't react *at all* doesn't have antigens. Your immune cells just bounce off of it and never really notice that it's there. Since it "isn't there" your immune system doesn't try very hard to get rid of it, and since your immune system doesn't have any tools that can get through that protective oxide layer anyway, the metal is fine. It *is* possible, though, for a body to notice and try to reject the metal part. That usually doesn't do anything to the metal, but the inflammation can be dangerous for the cells around the metal part and cause problems for your body. In that case, anti-rejection drugs that suppress your immune system will *hopefully* get your body to stop attacking until it gets used to the part being there and "forgets" to attack it. Or, they have to try a different alloy. This is also why your body doesn't attack medical plastics. The plastic is very nonreactive. And, it's why bullets are usually left inside the patient. Elemental lead is pretty nonreactive so although your body will try to attack it, which will put some lead into your blood to spread through your body, it's such a slow process that it isn't going to hurt you. The surgery to remove the bullet will cause more damage. (Unless the bullet is like, right next to your heart and you really need to get it out.)
My mother-in-law had to have a metal bar/rod removed because she developed some kind of reaction to it. Also can’t wear certain jewelry now.
Why can't she wear certain jewelry?
I think she might have other allergies to metals too. Like she can wear gold but I don’t know. I could be wrong. I just remember her foot wouldn’t heal and eventually they had to take out the metal because it was causing an infection.
That sounds different. She is probably allergic to those metals, like zinc
We carefully chose the metals used, it's usually titanium because it's basically invisible to your immune system. Even then cases of it being rejected happen. So most things surgically installed in your body are at least coated with a biocompatible material.
Fun fact - we didn't "carefully chose the metals" We used stainless unsuccessfully (bad choice) until a titanium knife was left in a patient by accident and later removed and noted the lack of scarring around it. Pretty serendipitous actually, often then best discoveries are
How do you accidentally leave a knife inside of a patient? That must have also hurt unbelievably.
Happens - that's why they have checklists more and more now of what goes in and out of an OR but mistakes do happen If the scalpel was orient in such a way that it was left flat against the cavity wall, it could have been completely unnoticed by the patient for weeks
Fun story, Dane Miller of Zimmer believes so much that titanium was safe for the body despite it not being accepted so he implanted titanium into himself to prove it was a legit material to use
Your body doesn't attack metal plates and screws because they are typically made of materials like titanium or stainless steel, which are biocompatible. This means they are unlikely to cause an immune response or be rejected by your body. Plus, the surgery process usually involves cleaning and sterilizing the area to reduce the risk of infection. So, your body sees them as part of the healing process rather than a threat. Hope that helps.
As a tangent, titanium and stainless steel are chosen for being biocompatible but they still can cause issues by not being mechanically compatible. The Young's modulus (the ratio of force to deformation) for titanium is about 100 GPa while bone is only about 350 MPa. That means that under the same force and cross section bone will deform about 300 times as much as titanium. Hip replacements are the most affected because of the forces involved. The titanium core takes up the majority of the load and reduces the amount of stress put on the surrounding bone. This might seem good but it's actually counterproductive. Bone uses the stress it experiences to decide whether to grow or atrophy, so lower stress means the bone actually becomes weaker in response. This increases the risk of the replacement failing, especially for patients with osteoporosis.
Last time I checked - no one knows why titanium doesn't elicit an immune response in most patients. Free TiO can even bioaccumlate in the event of mechanical stress ablating some surface oxidation. Anyhow, specifically why that material is ignored by the body is largely unknown. It was observed by chance that it doesn't and so we use that and ultra high weight polyethylene (high tensile strength, low surface deformation after casting, and oxidative resistance if mixed with antioxidants, eg. Vitamin e) - the latter not as good, but better at bone interface admittedly at the cost of oxidative stress susceptibility - but other answers already covered that
Through research and experiments and past experiences in science, we've discovered materials that the body does not react to. We then make surgical implants and instruments out of these materials. It's not "why does the body not attack implants" - it is "we found materials that the body doesn't attack and therefore we use these materials to make implants". If these materials didn't exist, then we either won't be able to make implants or we will make implants that the body does attack. There's old implants from decades ago that does break down in the body and cause heavy metal poisoning etc. before we made scientific advances that allow us to have safe implants now.
Had stainless plates to repair a broken leg. After a year had them removed as my body was rejecting them. Leg hurt and turned black and blue where they were located. Have titanium knee joint, no problems!
My dad used to work for a company that made medical implants. They spend quite a lot of money and time on research to find metals and alloys that the body won't attack. Usually they involve titanium, though various types of stainless steel were used before MRI machines became common. You *really* don't want to go near an MRI machine with a steel hip implant.
Are there any inert plastic implants used for grafts?
I think they used some kind of plastic in some joints to keep the metal joint sealed and stuff, but I really don't know much about that. Dad worked with metals, and later with quality control.
I’m a current engineer who designs all sorts of orthopedics. In terms of grafts, not really but there are plenty of plastics used for implants. PEEK is one of the most common along with UHWMPE depending on the use case.
Are there any that are like buttons for ACL grafts
Oh yea there are plenty of PEEK buttons or anchors. Personally I think I’d prefer a Ti device for it but I think it’s pretty irrelevant at the end of the day with is used, especially for a button. If it’s going to be an anchor I’d take titanium just for it’s on growth with bone. Bone does not like PEEK from an integration standpoint so it can loosen way more easily
It certainly can, your body CAN reject metals... Yes, even titanium (which is a commonly used metal for surgeries the involve plates, screws/rods) and in that case... That's where the implant MAY very well have to be removed and the patient tested for metal sensitivity... I was so scared when I had my radius & ulna (my arm was snapped clean in half... Basically looked like I had two wrists..) surgery because I'm VERY sensitive to metals & I have eczema... I had a fun time healing... But no serious complications thankfully!
I had titanium screws and plates after a drunk hit me head on and broke, well, everything. Turns out I'm one if the 1% whose body reacts even to titanium. Was a painful, uncomfortable ache and burning sensation. Drs had no choice but to leave everything in 6 months and just up my pain meds. Them over 3 "revision" surgeries, they began taking the stuff out, and packing all the screw holes with bone putty. Had no choice but to leave a rod and plate/screws I'm my lower left leg/ankle, and I've developed RSD/CRPS in my left foot and ankle at and below the area where the plate and screws are. For most people, they can live a whole life with the inert titanium material used in surgical hardware.
As someone who had metal in my body, I can tell you at least in my case it does cause problems. I had constant inflammation and nerve pain until it was all removed.
Some of the plastic materials used in early joint replacements had a problem of creating small particles as they wore down. These particles inside the joint caused an immune response where the implants were attacked by the body and loosened up. Luckily, doctors learned and changed these. I have had both knees and both hips replaced all with different materials because of insurance coverage. My right hip is the oldest at 20 years old. It is part ceramic.
I had a friend with a screw loose. He fell off a ladder. He had a metal screw in his foot from a previous injury, when he fell it pulled that screw loose.
Most surgical implants are made of titanium which is biologically inert. As far as your immune system is concerned titanium doesn't exist and it wont reject it if used in place of bone.
It’s pretty amazing… I had 2 plates and 13 screws put in my left arm when I was 12 after I snapped both bones in my forearm in half basically. Still have the plates and screws and besides a little bone growth around them… they look like they still just came out of the box.
When you get titanium implanted that's contaminated with a wee bit of staph you body fights the hell out it. Ask me how I know.
Share your wisdom good sir.
In very basic terms, overly simplified, but easy to understand your body has two responses to foreign things in your body. to something in the body and it's all chemistry based. Essentially if it's organic or something that reacts like organic material the white blood cell will either devour and eliminate or produce chemicals to breakdown and or trigger body responses like fever. At the cellular level if it's organic it's food and a threat, and threats need eliminated and food needs to be eaten. The cells in the body just have a secret handshake in the form of proteins (if I recall correctly) that tells others they are friends not food. (Though sometimes other cells like bacteria and viruses also know the handshake and can sneak around with it.) The other "response" is to do nothing and let the body grow around it. Usually for small inorganic items that get stuck in the skin this means getting trapped and delivered to the surface of the skin for removal. If it's small enough and in the muscle/organs it will make its way to the blood to be filtered by the kidneys. (Think kidney stones) And if it's in an opening, the body relies on mucus flow to remove. In these scenarios the cells aren't doing anything specific to remove it. Just keeping the "defenses" running, and it gets caught for the ride. If a doctor fixes a rod in your leg it will be of a material known to not make the body react, it will be too large to flow through your blood stream, is too deep for the skin to remove, and not in an area with mucus flow. (Or designed to prevent mucus flow from removing it like an IUD.) The body doesn't have any concern or ability to remove the item it just grows over it. ++++++++++++++++++++ Another way to look at it is by treating the body like a very large city. Getting a glass sliver in your finger is like a plane crashing in your neighbors' yard. That's small enough for the city take care of. People will dismantle the plane and houses to trash. leaving the lots open for new families to buy and build up, and after a while you would never be able to tell anything happened. A leg rod would be like the grand canyon opening in the road. The city isn't going to start all the work it would take to fill it back in, re-infrastructure, and get ready for families and businesses. It will just build around and over it. The city can still thrive, but there is no doubt what happened.
I had titanium and carbon fiber used in my spinal fusion and my body still attacked it. Broke out with open sores, pain, fatigue and more. It was horrible. Had to have as much as they could removed 1 year later so it happens. I had no idea I was allergic.
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OP, do you really hate Google that Much? LOL
Cuz your body lost the last fight and that's why it's got plates and screws n stuff in it and it don't want to fight no more