If you have exercise videos, or can watch one on TV, you might be able to do some of it with your arms and hands. Kicks become punches or lifts. Do them low to strengthen and high to bring your heart rate up.
When I first started learning to modify "normal" aerobics for my too-heavy body, one of the first things I learned was that if the movement is too much for you, drop the arms and concentrate on the feet. Add the arms again when you need to raise your heart rate.
The same works when you can't use your feet at all. Any arm motion above your chest will raise your heart rate and help you burn fat. That's what "chair dancing" and other seated exercise is all about. There is a whole community out there that can't use their legs at all, or who need to sit while exercising, and there are exercises for them, too. If you Google "seated exercise
" you may find some options that will work for you.