Hi Sally!
Sorry, I don't know much about Lumbar fusion... I had cervical fusion at C5/6-6/7 on Feb 14th. They used cages and plates, and I went back to work 3 weeks later. I do very heavy work (printing) and my Neuro said I shouldn't have any trouble above or below the areas where I had ACDF. My muscle spasms are almost non-existent, and I rarely have any pain. I had no physical therapy, and am doing well. My mother had lumbar fusion, and started having pain again, and we found out it was how she slept... she uses my method now...we call it the "knee pillow method" lay on your side, with knees bent, and place a pillow (small or large depending on your preference) between your knees. It seems to take the twisting stress off your lower back, and I have found I sleep much better. Since doing this, my mom hasn't had any more lower back pain.
Hope this helps!
Be well!
Dave