you might be able to get away with using a rowing machine ... that might help your cardio. As for leg exercises, try horizontal squats (if you have access to a gym) ... i'm sure there is a better name for them, but you basically lay horizontally and push off a foot plate. It's been scientifically proven that by working one leg, you will actually see improvements in both ... obviously not as much, but if you can't use both legs, then at least u are getting some benefit.