I had my 3rd spinal surgery in the last 2 years and this time he closed up with staples instead. what would be the reason for that? they hurt!

Scar tissue: Choice of closure method is completely up to the surgeon. For a third surgery, it can be somewhat more difficult to close through previous scar tissue, so that may be why the staples were used. I would recommend you ask your surgeon to get his viewpoint.

Ask your surgeon: There are a variety of potential reasons they were used. You could probably get the best answer from your surgeon himself, although there is not much that can be done at this point. I would let them know if they are particularly painful as it may be a sign of some form of complication. Staples in the back typically come out at 10-14 days, so at least it will have an end soon.