I'm sorry to hear that. Hope you're all better now in terms of your back and hands. Yoga relies very heavily on them.
Because Yoga has so many weight bearing type movements - down dog, sun salutations, etc. - I need to stay away from it for a bit. And then, in a few weeks when I'm ready to go back to it, I will be having eye surgery on my left eye so I won't be able to do it, anyway.
I was off yoga for more than a year a few years ago. I had a labral tear which they wanted to do surgery on. I said no and opted for phys therapy, etc. It took quite a long period of healing / recovery and I had to stay away from Yoga all that time.
I've never heard of chair yoga.
Is it kind of similar to using a pilates machine, as opposed to using your own body weight?