If it was discovered that I have 2 broken screws in my neck that were originally placed during cervical fusion surgery, does my doctor or the manufacturer bear responsibility?

The manufacturer or the doctor may have some responsibility.  If the screws have presented problems in the past, there will be lawyers who are pursuing claims about it.  It would be much more difficult to hold the doctor responsible.  The doctor would be responsible only for doing your surgery so incorrectly as to cause the screws to fail.  This is unlikely, or at least extremely difficult to prove.

Search the internet for bone screw litigation, orthopedic bone screw litigation, defective bone screws, or similar terms.  Contact some of the lawyers who pursue these claims and seek advice.  Even if those lawyers are not in your state, they can often associate with lawyers in your state or help you find someone.

Good luck.