I have had 2 fusions at L4-5 and L5-S1 (2nd one a year after the first one failed). Because I have 3 levels now fused (and still have terrible pain pretty much all the time - partially now due to the next 2 discs up being bad), I often have trouble with reaching for um... er... bathroom hygiene. 'nuff said. That would be one of the worst things, I guess. "Intimacy" with my husband is very-nearly extinct. Also have difficulty picking up stuff from floor, putting on shoes that need tying, clipping toenails, shaving legs, etc. I can no longer go horseback riding
(I used to LOVE it!) (and by the way, why aren't there any CRYING smilies available here?? That's what I *wanted* to put after "no horseback riding"). Also can't ride our ATVs anymore - well, unless you count putzing along on a road or very smooth surface "riding" - I call it BORING!
Can't water-ski (not because of the fusions though - just because of the d*** PAIN!) I'm permanently banned (by my NS) from anything "high-impact" and from lifting over 20 pounds, because of the stress on the remaining lumbar discs, which are already half-shot.
BUT, all that is just me. Some people go on (after a fusion) to live pretty normal lives.
Good luck with your injection.