At six weeks post op I had no bone growing at all from my spinal fusion. I don't know if that is normal or not. He already mentionied that if there wasn't any bone growing he might have to go in and "tighten" my screws. Hmmmmm I do worry a bit because my sister had had a similar fusion years ago and the fusion with her own bone didn't take. Should there be some bone growing at six weeks?