I was going to ask... Have you tried alternative forms of treatment. Surgeons told me I needed to have both my knees REPLACED. Then I found a good Osteopath who treated me just a couple of times, right before I began my diet and exercise. Part of that exercise was walking 5-10km almost every day. Before the Osteopath I couldn't walk 200 yards without severe pain, and hadn't been able for almost three years. Now I can climb 24 flights of stairs without stopping...
A few years ago, other surgeons wanted to fuse my lumbar vertebrae. I lucked into meeting a wonderful physiologist who convinced me to try her exercises before I gave into to the surgeon. In just a few months I had taken off the back brace I was in, and stopped all pain medications. You know how active I am now.
Please consider it before you permit surgery.