I don’t know about neck fusion but I would think you could have the shoulder replacement. I have needed the shoulder replacement for many yrs but because my back pain is so severe I opt not to have it . I don’t think I could tolerate that much pain in my shoulder and my back . You would have to have a big comfy chair lounger for the replacement because you can’t lay down for a while, no way will my back hold up sleeping like that . I still can do everything I need to do with my arm except bring it up over my head and my arm doesn’t hurt so that the way I feel about it plus I’m 78 yrs old and I have smoked all my life so the surgeon would not operate on me until I quit for 3 months I’ve never stop