Luckily, I can still bike, I'd be a total basket case if I couldn't. Longer road bike rides, in the 40-50 mile range at a decent pace so you're out for 2 1/2 or so hours, would help you keep your aerobic edge along with keeping your hams, gastrocs, and quads in shape. There are a some muscles, however, that aren't used in both running and biking (different portions of the quads, foot muscles, etc.) If you try it, make sure you get really stiff biking shoes and clipless pedals so you have no foot flex. Put the ball of your foot slightly ahead of the pedal axle to decrease tension on the PF. Pedal in smooth circles, or even accentuate the upstroke and forward/backward pulls while lightening up on the downstroke. Also, drop your heels for a couple of minutes every 20 minutes to keep your heel cords (achilles) stretched out. This is important, since PF and tight heel cords often go hand in hand. There is a very good biking book called "High Tech Cycling" that talks about a lot of this stuff and goes into great detail on the subject (VO2 max and heart rate, caloric expenditure, best bike setups, cycling injuries).
If you are interested in trying it, find a really serious bike shop where the roadies hang out, I'm sure they'd be glad to help you. They're usually a great group of people and are always interested in growing their ranks.
It's more expensive than running, $hundreds vs $70, but it gets a person out on the road again and is a kick butt aerobic exercise of done right. I still do my favorite run courses, but just on a bike now for the time being.
I would suggest trying the best sports medicine facility that you can get yourself to, in order to find out what suggestions they might have. They usually staff physical therapists and orthopods that are well versed in running injuries like PF.