You NEED some kind of suspension when you have 4 wheels on the ground, so that a bump or hole doesn't pick one wheel off of the ground.
With 3 wheels, the trike will roll with the bumps. In theory suspension might help some, so you aren't moving the center mass as much, but if you get the tire inflation right, the bumps aren't that bad.
It may take some practice getting used to lane positioning.
I don't remember bumping a trike wheel over curbs and such, although I didn't put that many miles on the trike. I do occasionally bump a trailer tire somewhere it isn't supposed to go.
I don't think I'd go with suspension for general pavement riding, although you may have a unique situation in which suspension might be of benefit.
I'd encourage you to find a trike to rent, borrow, use, test-ride for a bit before making the final decision, and if you're still riding now, do it before the surgery.
Is there a local trike shop that would have a variety?
It might be fun to visit Utah Trikes sometime.
