It sounds like you have taken Pilates prior to your surgery. If you felt comfortable with your trainer go back to them and ask for advice, as they already know you.
If you attended a class and are looking to go back to a class, I would recommend start with private sessions and an experienced trainer. The Pilates Method Alliance would be terrific start to find a quality teacher.
In either event, start slowly, with a moderate pace and listen to your body.