I need to start an exercise program but have knee issues (no cartilage in one) and need something with low impact that I can do indoors at home. I've tried walking but can't do much on pavement without paying for it later with my knee. Any suggestions about machines or videos or programs?

Denise Austen has some good low impact aerobic videos out. You could do everything but the ones that include bending the knee.

My boyfriend had that no cartilage thing but got an operation last month, his physio says to do weight attached to the ankle and cycling, you can get operation to replace curcia ligament (spelt wrong but sounds right)you have to build muscle to compensate