Loosing weight with knee injury

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I have multiple surgeries comming for my right knee I cannot squat, walk long distance, or run at all. Also cannot do push ups, I am gaining weight and trying to eat right. Been going on ellipical (spelling) 4 times a week but nothing is happening, situps doing 80 5x a day. I need help =( what are my options? I need to loose weight in my belly and hips (had a baby 6 months ago) any excersizes or tips? Running used to be the only thing that zapped these problem areas but thats not an option anymore.