Make SURE each time you squat your tighten your abdominals!
Take in some air before you unrack the squat bar, and before you descend.
And wear a belt.
Tighten your abs right before you unrack the squat bar and keep them tightened throughout the whole squat. Don't loosen them until the bar is back on the rack.
Wearing a belt and tightening your abs will support your whole low back and everything and help to keep direct pressure off the back.
Do a bunch of lower back and ab work, nothing heavy, real light, high repetitions.
Use the same breathing air in and tightening the abs for dead lifts and any compound lift you do.
If you don't mind me asking, did you go home the same day as your surgery?
How much pain were you in post op?
What were your limitations ?
Are you pain free now?
I'm about to head in for the same surgery.