Okay, I took a quick skim of this. Disclaimer: I've been really sick the last week and I'm not completely recovered, so my mental capacity isn't where it normally is yet.
Is the concept sufficiently original, interesting etc. If not, what could be modified about it.
I would have to say no. It seems to be a wheelchair that does terrible things to able-bodied people, and also gives hallucinations/nightmares… for some reason? I personally would need to see more of a reason why all this terrible stuff happens, rather than the item just being horrible for the sake of being horrible. We already have a lot of articles that describe body horror in plenty of detail (most of those popular ones written 8+ years ago rely heavily on detailed body horror) and this doesn't stand out well to me.
Does it flow well? I had issues with the order of information and am a tad worried it feels as though it jumps from concept to concept.
It flows okay, but the whole of the article seems pretty bland, so that in itself is less of a concern than the concept itself. I recommend getting the base idea polished up in the Ideas and Brainstorming forum before you try fixing the draft.
Are the technical descriptions, basic as they are, believable? How can I add more detail without a) saturating the reader in jargon and stats and b) getting all the terminology utterly wrong?
I'd say they're believable, but I kind of glanced over most of the detail because I'm not a big fan of long descriptions that basically amount to "also some horrifying painful stuff happens to the victims". So far as terminology goes, you can always consult research sources to see how real professionals would describe the conditions.
The expungment, however, needs work. I feel like in the first instance you could use [REDACTED] or just blackboxes (since it's a name that was censored, yeah?) and the rest should be taken out or reworked entirely because they feel kind of like authorial cop-outs expecting the reader to fill in the interesting information on their own. I recommend reading over this guide on interesting expungment for some tips.