Honey, unfortunatelly no tests which shows all damages with 100% accuracy.
I went for my spinal lurabar fusion with other work on a spine but it was never mentioned something about same area you have problem as well.
My surgery instead of expected 6-7 hours was almost 10 hours. My Dr was shocked when they opened me up how much damage i had right in that area.
I had so many MRI, Ct, discogramm, you named and it was never even mentioned any problems there.
Because it was so bad, he done much more work than I expected.
So this is just my experience I want to share with you.
Believe or not i had a second fusion surgery since than but that area is still my concern: hard to seat and than get up especially if you seat longer than you suppose to.
Buy yourself a nice special pillow under your behind, it helps a lot to seat.
BEst of luck to you!