I have a ruptured C3-C4 that's never been fused and the disk particles have been in the nerve canal for 10 years and I was afraid to have surgery when I saw the screws and plates the surgeon brought into to my visit. I also have 25% spondy that I have been told to wisely ignore.
Could be defective screws
Screws not put in properly.
Could be over torqued screws
Could be the screws are under more stress than they were designed to be under - overweight and over active person putting stress on them or a bad fall.
I can only imagine what you are going through and for some reason my necks hurts reading your post.
I hope you have insurance and if so I think you need to get it fixed there is no turning back IMO (just my opinion) and that's another reason I never got my my spine fused in-case complications arose and I was stuck with no insurance. It would be pain or going broke fixing the neck again.
There could be a product liability (faulty screws) as opposed to malpractice (the screws were put in wrong).
I will make a big assumption that your spine has not stabilized and your fusions may have come loose. If the fusions never take due to smoking, being overweight, or that the bone just doesn't come together, then that will add stress on the screws also. If your spine is stable and the fusions took, they may be able to just remove some of the faulty hardware.
This article shows a 12.4% breakage rate in patients and tells me titanium screws may be overrated for what they are asked to do for some patients.
http://www.springerlink.com/content/e75te6tv8d2jguty/
IMO, I think you are owed at least a new operation to correct the problem and that's the course I would take unless it was obvious your surgeon messed up or those screws were defective or not even titanium that a metallurgist will have to prove. That's a long operation and I'm sure a lawyer would be needed to force that done for free if he isn't volunteering to fix it. If you have insurance, that's a good bet to get it fixed by another doctor.
See if a pain clinic would be recommended also.
I wish you the best.