You can definitely loose weight in the aerobic span (about 130-140 BPM) but if you want strength and muscle building, you will need to do something more anaerobic. I would suggest alternating. You can do aerobic activity for a few days/week, then do strength building on the days you don't plan to do light cardio. Keep in mind that muscle burns calories simply by existing, so that will help with your metabolism if you end up training for strength. As far as specific exercises go, I don't know the extent of your particular injury, so it would be hard for me to give you anything concrete. I would just say stop when it hurts, as in not the burning kind of hurt, but the injury kind of pain.
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