Nutes should be alright. Yes double to triple the size during budding. I saw no difference with 24/0 when going to 12/12.
Good luck with the knee. My mom had hers done afew months ago. If your pain pills don't work stay on them to change. It's going to hurt and be stiff but do your walking and exersize. it will pay off in the long run.
Good luck with everything.