If anyone has the above mentioned fixation system, or the version 5.5, or any system that uses a large rod mounting post screwed into both sides of the ilium: If you sleep on your back, do you feel the hardware? The illustrations of the system show the largest of the rod retention posts are the two that screw into the ilium. I am confined to sleeping on my back due to neurological problems after a 1998 lumbar fusion. I am thin, and worried they will be painful. TIA, RJM