Pcad, I'm really sorry about your condition. Get well man.

Although those elliptical machine-like bikes might work, I'd actually avoid a recumbent bike because it still does stress the pelvic area, you may still exacerbate your condition even on a bent.

I think the ultimate solution to keep you on two wheels would be to find something that has you totally off your posterior, and in a prone position. It looks like there are a lot of options for you: