My experience C 5-6 fusin did put more presure on thorax and have more steniosis there now then before. Although I started with a curved spine. L345 and s12 went out years ago and it took me five years to fix with stretching. Can not seen to get thorax area to relax,the clavical. I did not do surgery that low, try stretching and possibly pilates or the new strecth machines DX somethings. It took 5 years to get back to "normal" activity level. Long time but better then fusion I think. Syatic pain is a pain, it gets better though if you stay in positions that do not cause it. That is why it takes a long time. Wish you the best.
Circles.
I am not sure about thoracic, or cervical but I was told by my husband's neuro-surg that it could weaken the areas directly adjacent (above and below) to the fusion/fusions. Hope that helps... My hubby is about to have a double level L4/L5 and L5/S1 fusion in a couple of weeks. eeek! No other choice at this point.