Exercise for the Mobility Impaired- my knees

This is the first time I've posted on this forum and I'm sure this question has been asked, but OH's search feature just sucks.

I have osteoarthritis in both knees and am nursing a cartilage tear in my right one.  I need to incorporate some exercise in to my pre-op plan and am wondering if anyone knew of some resources (DVDs, etc.) or exercises for those with my sort of issues.  I'm aware of working out in the pool and have in the past, but my access to anything other than my apt. complex pool is hindered by my finances.  Any help you could offer would be much appreciated.  Thanks in advance.

I had mucious tear and had arthroscopic knee surgery in March. I also had 3 injection series of snyvisc in the last 3 weeks. the injections had made a big difference. I highly recommend a recumbent bike it isnt hard on the knees. I love my recumbent bike I do an hour a day on it. I was in physical therapy and that is what they put me on it and then I got one for easter and been using it every day. I still not doing the dvds yet. I also have plantar faciitis still having issues with that. Hoping that will be resolved this summer.