Arcadi, I got an old racing chair frame and tricked it out with new wheels, seat cushion, etc. Soon as there's no snow and ice on the streets I go wheeling around. In the meantime I can "walk" more a shuffle, with well padded cross trainers on the treadmills. How much function do you have below your injury? I got mom one of those static pedal sets and noticed you can use them on a tabletop for upper body cardio.
Drop me a pm and we'll talk.
Brock