I THINK, in extremis, the hospitals use the standing machines used for animals. Don't take that as gospel tho...
She'd certainly never fit in a standard MRI (except maybe a toe at a time) but I don't know how useful such diagnostics are with enormous amounts of fat to penetrate. Soz for PL, but I fecked my ankle once and just the swelling made the x-rays confusing.
These size people tend to be in real trouble when they finally get to a hospital. Even if they have gone to the ER weekly with colds or pimples, they avoid any mention of obesity-related problems like the plague. Then, when crisis strikes, they won't fit on a trolley, in the ambulance, on ER beds, on operating tables, let alone in diagnostics machines. I live in a country with universal healthcare and the necessity for bariatric equipment is putting a serious strain on that system, but this level of morbid obesity is beyond most bariatric equipment and even limits where patients can be taken.
She already has serious problems with her feet. I think
@Five Bladed Knife mentioned "Charcot feet" (I don't know enough about it outside MCT and CVT so they could easily be right) but she's constantly banging on about heel spurs. They are not the problem; the problem is weight -,she has collapsed arches and likely raging plantar fasciitis at the very least - the strap of tendon under the foot simply can't support that kind of weight. Her feet are terrible splayed, they "roll" outwards when she walks (classic PF sign) and her shoes have no support; they're already blown at the sides from that rolling motion. And no way can she reach her feet to even put supportive strapping on.
I know she writes us off as hadurrrz, but I don't hate her at all and certainly not for her weight. The real issue is that we tell the truth, and she knows it. She's just about young enough to not be feeling too much damage but if she lasts another five years she's going to be in a world of pain. No doctor will put artificial hips and knees into a person this size, it's too dangerous. But those are what will blow next, and her feet may already be beyond help. PF takes forever to heal in a person of healthy weight (people who run/walk on hard surfaces get it) but the only thing she's doing to help it is not moving much, and any benefit from that is destroyed the second she stands up.