A few years ago I had not one, but two back surgeries. The first went through my stomach, the second through my back to put in a rod and screws in order to stabilize my spine. The surgeon told me that if I were to get pregnant, I would have to have a C-section. I would like to know if that is true. I am ten weeks pregnant and due in November. I've never had a C-section before.
In general, back surgery doesn't preclude a vaginal delivery. That said, your surgeons felt strongly about this or they wouldn't have said anything to you, and the surgeon who was there at the operation knows your anatomy best.
The answer to this good question will need to be figured out by your OB, in consultation with your surgeon or someone else familiar with your procedure. Talk to your OB early in pregnancy, so that appropriate consultations can be obtained and you can understand the specific issues for your body. Good luck to you!