Disability

You could do a hand cycle machine for sure. You might also be able to do a recumbent bike or rower, if you adjust where your feet sit so the pressure goes to your heel instead of the ball. Obviously, I don't know your specific needs so those might not work for you, but it's a place to start.

I would also look up the terms seated or chair cardio to find a number of circuits that people have created.

Are you able to walk unassisted for long periods of time?

I had a calcaneus fracture that left my heel severely swollen with arthritis. So I have to find different exercises too. I suggest looking up chair cardio, or couch cardio. Either if these can be made more difficult by using weight's on arms and legs. I also use a exercise bike, finding a good pedel is key. Kettel bells are awesome, love them!!