Fusion transfers the cumulative stress, wear and tear distributed between several newly fused vertebral levels onto the next lower level. I'm sure you can see the problem there. However, people in severe back pain will understandably make a lot of concessions for a chance at escaping it.
Fwiw, my 13 yo daughter was fused over the majority of her spine for scoliosis correction last month. She's doing well but I worry about her future.
