Aw, my heart goes out to you. Yes, I think I can explain what your dr meant by a "simple fusion". Before they came out with the rods, the pedicle screws, now the cages, none of this crappy hardware was around to be put in the body. The fusion was done here in my town by sometimes an orthopedic & neurosurgeon, they worked as a team. Thats when insurance companies allowed drs to be drs. They would either take the bone graft from your hip or from the bone bank. That was your usual fusion, until they came out with all the hardware. When they first started using hardware not everyone was a candidate for it. They were really selective about who got hardware and who didn't. Then, the next thing you know everyone needs hardware. Wrong, not everyone needs it. I would never consider the hardware personally. You are trying to trick the body into accepting something that shouldn't be there and its a no win situation. I know personally of numerous people who had instrumentation surgery and regretted it. In a year every single one of them was back in the operating room having the hardware removed. They had intense pain from the hardware every stinking day. They went thru hell recovery wise and never got any better. You have had previous surgeries so you know what I am talking about. The drs forget to tell patients that the body can and does reject instrumentation and the rate is very high.
Most people complained of the graft area in the hip as being more painfull than the actual surgery. That was the biggest complaint. You know about the nerve pain, let it go too long and it can become permanent and no surgery can fix that. You can also end up dragging a leg around forever by waiting too long, this happened to a good friend of mine. You can loose control of your bladder & bowels.
It takes a good year to totally heal and recover from a fusion and don't let anyone tell you any different. You may be even longer since you have had 2 priors.
Above all find yourself a good neurosurgeon to do your surgery. These guys are alot more qualified to get in there around nerves versus an ortho. Ok, sorry its so long, my 2 cents. I have seen thousands of these done.