I am 6 mths. post op and am still sitting with my blow up lumbar pillow , pretty well inflated, in my low back area when I sit. I cannot sit all the way back in a chair without it. I do my stretches and strengthening. When they fuse the L4-S1,does it change the lower lumbar curve so you can't sit back without a cushion or is this muscular and passes as time and healing progress?