Translation: Lots of theories and suggestions about how automail feels, the logic behind it’s design, and how it works from a medical and structural engineering point of view.
Also, there are diagrams. Fear the drawings of Edward I produce at 5 AM. Fear them.
X-posted to various other communities and my personal LJ.
It’s true that FMA is a fantasy world, but it's often stressed that it's not a magical fantasy world, it's supposed to be scientific. Some things I can deal with in the canon under the "it's anime/manga" excuse, that is to say I don't need anyone to justify for me why Armstrong sparkles. I know that's just because it's a sight gag. Nor do I really need anyone to explain to me why transmutation circles glow, or why transmutation makes noises, etc. I can also lump "how automail works" into the "it's an anime" excuse (however I will point out that if someone does have a nifty explanation for why transmutation circles glow, I am happy to entertain them. I’m just saying that I don’t need it to be explained to me). Nifty gadgets are sort of something you just suspend disbelief in order to accept them.
…But that doesn't mean that I don't like seeing the automail treated more seriously. When I go into analyzing it, I come to the conclusion that the author basically thought it was cool, didn't bother themselves with the actual logistics of prosthetics and how they work, because that isn't what the manga/anime is about, and it's not what the author was interested in exploring (there's an interesting idea. Manga about prosthetic limbs!). Keep in mind that this essay is not a critique of the author nor of the anime itself. Every work has issues that fall to the wayside because they are not the central focus of that work, and I feel that automail is one of these issues in FMA. I don’t expect or need them to explain it better, but for my own writing purposes, I like to give it a sense of internal logic. Hence, this essay and its contents are things that I try to keep in mind when I write fanfic ^^;
First, basic diagrams:
So the first thing that came to mind when I started to think about how automail works is how it attaches to the body. Apparently the wires inside the automail somehow attach to the nerves of the body in order to get their energy (they operate on the electricity created by nerve impulses, I believe?) and to receive commands from the brain...and there's the limb itself, and then there's an automail port, which the limb can be easily (but painfully) attached/detached from. So the port is probably the hardware that is most firmly installed. Installation is probably very painful, especially in a case like Edward’s shoulder – a great deal of flesh and bone probably needed to be excised in order to make a firm base that could support the weight of the rest of the arm. So if his automail is removed, I imagine that Ed probably has a considerable chunk of flesh missing from his right shoulder.
Also, the firmest and most logical way to anchor the automail limb to Edward’s body is that the automail bone replacing his humerus (see diagram numbers 3 and 4 in this essay) is probably screwed onto either some of his ribs, or onto his shoulder blade (scapula) or possibly even the acromion. (See link for details on shoulder anatomy: http://uuhsc.utah.edu/healthinfo/adult/spine/anatomy.htm ) This would replace the glenohumeral joint (shoulder joint), but would not need to be as functional as the actual joint is in real life. Metal pins would hold the automail bone in place, and the rest of the arm would deal with all the joint stress. The top of the automail humerus is probably a feat of automail engineering ingenuity, since it would need to be long enough to attach to a solid bone, but it would also need a flexible spot in it that allows for the patient to rotate their arm up and down as well as side to side. It’s replacing a ball and socket joint, after all – the difficulty only occurs because of the inability to create artificial ligaments and tendons (at least, I’m assuming they can’t make them – if they don’t have plastic than they wouldn’t have those, either…and I’m assuming that they don’t have plastic because if they did they would use it for automail parts, not make them completely out of heavy, expensive and impractical metal).
This attachment is probably the main root that keeps the automail arm in place, however, it requires support (I will address this later) to prevent all the weight and stress from being placed on the delicate connection that keeps the metal humerus attached to Ed’s shoulder. Weight needs to be evenly distributed or the automail would tear off of Ed’s shoulder at the slightest stress. The good thing about having this inner support is that the automail humerus then passes through the inner and outer port. This is all-metal junctions in the apparatus, so there can be relatively reliable airtight seals (rubber? Membrane?) made at each junction and each level of construction to prevent outside elements from getting inside of the port and at the raw flesh beneath it.
The reason this set of screws would be different from any other screws I mention later is because they are inserted directly into the bone, beneath the skin and muscle – kind of like when you have a metal pin in your femur because you broke it when you were eight? Well, not exactly like that, but along those lines. The issue with this is that it makes automail removal incredibly problematic, and while it does hurt in canon, they seem to just pop the arm and leg on and off without too much difficulty. Realistically, when the arm is removed, it should be entirely modular and not come off in one chunk. The humerus automail bone of the arm should realistically remain attached because the procedure for removing it is too invasive for regular maintenance/repair. So when Ed gets his arm taken off, he should have a metal rod sticking out of his inner automail port. Without the wiring it wouldn’t be able to move, so it would probably be strapped or locked into place somehow.
Removing an automail port probably requires some major surgery...because considering the technology of the time, I'd venture to say that they probably still amputate limbs fairly regularly in Amestris due to lack of medical knowledge. They must have antibiotics (otherwise Ed would be dead a hundred times over) and disinfectants, but the medicine does still seem very primitive.
Any time something (a tube, a wire, metal screws, a plate, etc.) has to pass through the skin barrier of the human body, there's a huge risk for infection. Grafts can be made between skin and other organic things, but automail seems to be all metal, so skin can't grow onto automail. Even something as small as a needle that has to puncture skin can cause problems and get infected...let alone a huge metal thing jutting out of your shoulder socket.
Also, it's painful to have something going through a rip in your skin, obviously. The wound wouldn't be able to close, it would have to be kept open. So I think that the inner-most part of the port is probably affixed to the skin with some form of adhesive (it might need to be re-applied by the wearer of the automail periodically) to keep the innermost part airtight. That is to say, there's probably a sterile inner part of the port where the flesh is all open and exposed, and it probably hurts like a bitch, but it's generally safe because the metal is sterilized...but every few years someone with automail probably has to get it all opened up and cleaned.
Outside of that part, you've got the actual outer port, and here you run into the problem of structural support. Ed's arm is the best example because it's the most difficult thing he has to deal with, I think (the leg is much simpler). He doesn't have any remnant of his arm at all, just the bones of his shoulder, so the entire arm has to be made from scratch. The arm is heavy, it needs a strong supporting structure to keep it from falling off.
I think that the visible metal plates that cover most of Ed's chest are just there as support, they don't actually attach to his skin. I think that most automail has at least four layers to it. There's an innermost 'bone' layer that's just simple rods, there's a layer of wiring, there's another layer of support (casing to protect the wiring) and then there's an outer layer of support and additional casing/protection to help it stay in place.
The outermost plating probably comes of easily - I would venture to guess that, realistically, automail owners should take the outer plating off every night in order to clean inside of their automail, depending on how delicate it is and which limb the automail is replacing.
Ed's arm is probably inserted to the socket of his automail port, but without additional support it would fall off easily, and all of the stress of weight would be on the socket, making it wear out too quickly.
So you have the plates that cover his chest and part of his back. They're sort of slip-covers, if you will, something to brace the rest of the automail. There's a part that nestles right above one side of Ed's collar bone, so I think that must have a metal screw there to keep it in place, and it's probably very uncomfortable and very prone to infection, but it's a small item so it's not lethal.
There are also probably screws in Ed's shoulder blade (or in his ribs) that attach it to the plate on his back, since the shoulder blade is an important part of how our arms move. Those are all probably considerably painful, although it's the kind of thing that, once you've had it for years you sort of stop noticing that it hurts, because it's normal for it to hurt. It’s also possible that Ed had to have his right shoulder blade (and the muscles attached to it) removed when his automail port was installed, since with the rest of his right arm missing, that bone and those muscles would have been attached to nothing, and probably caused complications later.
The other thing you have to consider is that these slip covers cover skin and not metal, so that means that you have a tightly covered area there, where heat and moisture accumulate, so that's why I say they probably should be removed every night. Otherwise the skin would probably rot eventually because dark heat and moisture are never good for human flesh, especially not when it's near an area that's highly likely to be infected.
So heat and dirt and sweat and water and anything else you can imagine builds up under those support plates, so it's probably very important to keep them as clean as possible, but because of the screws it's probably very uncomfortable to remove them every night, so a lot of automail owners probably suffer from various skin problems around their automail ports, just because even if they're supposed to, keeping up the maintenance is difficult.
Then there's the weight issue. I'm firmly convinced that Ed's belt is a back brace. It's pointlessly wide, the design resembles a weight-lifter's back brace, and it shows no visible attachment to Ed's pants at any time, so therefore it cannot effectively hold them up - and therefore is *useless* since belts are generally intended to keep ones pants from falling down (and Ed's pants are too tight to need a belt..).
It would explain why Ed's posture doesn't suffer at all, despite his heavy automail arm, which really should make his posture go to hell…but he's got the brace so that helps him stand the weight. As for the leg...because Ed had a stump left, it's attachment is much easier and doesn't require as much support...also, the leg is constantly being stepped on, so the pressure of Ed's own body weight on the joint will keep it fairly tight to Ed's body..though it probably hurts like a bitch, because it would push the raw part of his stump down into the metal of the automail, and probably pinch the nerve connections inside of the port. This might explain why, whenever Bones does really high quality animation of Ed, they make sure that he limps a little. But there are still support plates on Ed's thigh, flat metal areas that cover the port and some additional flesh (another spot where moisture and debris can accumulate), probably to keep all the stress from remaining on the inner port, again….And so that when Ed's weight isn't on the leg, it won't go flying off to the front or back when his leg swings because it's braced to his thigh with the shell part.
...but anyway, that's essentially my automail schpiel, more or less. I like the idea of considering it more realistically for many reasons…One of which is that it makes Al's motivation a lot more sensible, because then it's not just "I am going to stubbornly insist on fixing you when there's nothing really that wrong, automail is a livable solution", it's "You're in a terrible amount of pain even though the automail is a fine substitute, I still need to fix you and make things right".
Additional point of concern raised by Jade Pen: Dealing with automail-caused pain.
This next part is entirely theoretical and is just my logical progression of the automail system I’ve discussed above. There isn’t anything in the series that suggests this, but there isn’t anything in the series that denies it either, but as I said, this is totally theoretical, but perhaps a consideration some people may be interested in working with in fanfiction.
Ed might use some sort of topical anesthetic cream around his automail port to help numb it..but that might make him clumsy, too, due to lack of feeling in the nerves. Another possibility is that he uses a local anesthetic injection to numb the nerves inside of the ports. If so there's probably a spot in the inner port specifically intended for the insertion of a syringe.
Expense of such medication is unarguable - automail supposedly costs the same for them as a brand new car costs for us in our world, so most people probably just live with the pain. The ability to carry syringes around in their hectic lifestyle (considering that they have metal, but I doubt that plastic has yet to be invented) without breaking them is slim to none. But that’s what alchemy is good for, after all. If they break, Ed can just fix them.
Knowing Ed’s personality, he would avoid using painkillers at all costs, considering that he dislikes needles, and also he would hate to slow down his reaction time or dim his mind at all, both things which painkillers tend to do.
It’s also entirely possible that the syringes wouldn’t need metal needles (though metal is the easiest to sterilize I believe, so it’s the most likely material?) because they wouldn’t need to puncture flesh. This is because there’s probably an insertion point for injections into the inner automail port, and like when a doctor adds an additional drug to an intravenous line, one doesn’t need to puncture the skin again, they just inject the new drug into the bag holding the fluid that’s being intravenously fed. In the automail’s case, they could just inject fluid into the inner port and it would either coat the flesh and nerves there and serve as a topical anesthetic, or there may be a permanently attached needle within the automail (there are already so many things sticking into Edward, one more can’t hurt).
And a suggestion lifted directly from Jade Pen: Perhaps this is how Edward got his fear of needles? One of the people of Resembool (likely not Pinako; perhaps Winry or Al?) did it wrong the first time, and it hurt a lot more than it should. Mrm... perhaps Alphonse takes it upon himself to apply the injection at night, while Edward's asleep, since he himself doesn't?
It’s entirely possible that Alphonse would take a lot of the maintenance upon himself, because Ed would be too lazy/negligent to handle it consistently, and it’s been shown that Al takes care of similar things (ie: buying food for Ed before train trips).
And…that’s it! Please forgive any incoherent and the fact that the structure of this essay is sort of all over the place. Structure has never been my strong point, and I’m doing this out of my sheer love for all of y’all, so…yeah. I need to go do homework now. XD.
Comments? Questions? Critiques?