Someone a couple of months ago suggested it wasn’t a back brace, but this:
https://www.medgadget.com/2017/04/hill-roms-new-monarch-battery-powered-airway-clearance-system.html
The Crooked Hag, at that time, was wearing very loose coats & had big scarves draped around her shoulders ... a couple of pictures showed something bulging up in the shoulder area on her back & it really looked like one of these things. It was obvious that the huge scarves were an attempt to hide the outline of whatever she was wearing. This sort of fits with the notion that maybe something respiratory is going on with all of her coughing. The outfit she’s wearing in the video with this article is a much closer fit than the ones she was wearing earlier with the scarves.
Could be. Looks like it is used for cystic fibrosis, but could be used for other conditions