post cervicle fusion results

My question is one that all of you would like to have answered. I had a fusion of the c4c5 18yrs ago, and was able to work as a houshold mover and drive a semi truck for ten years. Had many falls,head bangings, and things such as sewing machines fall on my head during that time. With little or no problems until a fall in 2004 from 8ft  to the concret below.
I was self employed at the time and as with the other falls and accidents I tryed to walk it off. I did report it to my insurance co. and when I could see a Dr. to see if I had broken any bones. No broken bones were found, but the pain in my lower back,middle back and neck was to much for me to take.
So I shut down my business, had to sell my Volvo truck, and hope that Workers Comp. could get me back in shape.
Without boring you folks with California's Workers Comp. system. I semply well say that I spent more time with there lawyer than a docter. Note, I have four surgens saying that the fall aggrevated the C5-C7. area which has caused pain, numbness in my left arm and hand.
My Question is,( because I had a fusion 15 years before the fall, the insurance co. is not liable for the neck.) How long should a fusion last, before causing DDD . Does everybody get pain after fusion?  Are there studys that prove this?
Please, If anybody out there can shed some light on this, It would help me a great deal.

[richmill1]

my surgeon said the said the chances of adjacent joint disease arre 3% for 10 years..I think the problem is not your previous surgery..index finger and third finger are related to c6   god luck