I had a spinal fusion L5-5 six months ago. It has been a long recovery but definitely worth it. My surgeon did a TLIF type surgery which has minimal cutting to the support muscles and usually a faster recovery. I was on Tymlos at the time because my bones were not great either. The first 2-4 weeks were the most painful. I wore a back brace 24/7 for 6 wks due to the osteoporosis.
After 3-4 weeks I took 5-10 min walks in the driveway with my walker increased time gradually. I started PT at 4 mos out and now at 5 months , I graduated PT and have been released by MD. If you want more details let me know.