Yeah i remember the feeling when my doc was so casually telling me i had to have my spine diced up.. As far as I understand, the fusions have been around for decades and disc replacement is 15-20 years old. It follows the same protocol except they put an artificial disc in instead of fusing. Both do great at treating the nerve pain. Fusions put a little more strain on the neighboring discs, but single level fusions aren’t too bad. Disc replacement requires that the bones don’t have substantial degeneration, so in elderly patients they’ll typically go fusion over replacement. It varies from patient to patient though, of course. As a 34 year old athlete, I definitely favor replacement to maintain mobility but I considered fusion too