I have two fusions. Nowhere near the issues you have but I certainly would seek a second opinion. Whole spinal fusions are very successful in some cases but they are very BIG operations. I've seen some wonderful results on cases for people on TV and am amazed at the successes there. Fusions leave a lot less mobility and you need to take care how you perform many things in your daily life-from picking things up to exercising safely.

Since you are very active it will be vital that you learn how to properly maintain a safe level of activity and keep your fusion safe and sound. It won't be magic and feel like all is fine. There will be changes, restrictions, possible arthritis, and some risk as in any surgery. To embark on something of this magnitude begs for at least one other opinion from a well respected doctor (or more until you are comfortable).

Fusion makes the disks just above and below the fusion more sensitive to stress and strain. You must be careful how you do things so as to minimize the stress on these disks that now do all the flexion work. You must sit, bend, sleep, exercise in certain ways to help protect your un-fused disks.

I had fusion of c5-6 and L3-4 L4-5 and L5-6 was calcified. So I do things differently but I do pretty well. I got a car with a back up camera so I don't have to turn so much, I must put eye drops in lying down to as not to throw back my head and strain the c4-5 and below c6 disks.

I decided to have surgery only when I got to the point that the risk of death and paralysis was worth relieving the pain. In your case you need also to minimize further damage. A second opinion might make you feel this is the right decision or might open other possibilities.

Whatever happens I wish you all the best. I know it's not easy.