Hi oakleygirl and a belated welcome

I've been off the computer for a while recovering from a terrible cold so I missed your first post, but I wanted to say hi and offer you my support.
Retro- and anterolisthesis refer to the upper vertebrae being translated either to the back or front of the lower vertebrae. It looks like you have some loose pieces of disk material in there, some scar tissue. Your disk at L5-S1 is bulging, there is some degeneration of the facet or vertebral joints (i.e. bone degeneration), there is narrowing of your spinal column. Your L4 vertebra is slightly translated toward your front when you bend backward, but it moves back into place when you bend forward.
Hope this helps... I don't have any medical training so take it for what it's worth
Now that you've had the diskectomy, and hearing the MRI results, I don't know how many options you have. You have scar tissue and pieces of disk in there as well as the other problems. I don't mean to sound pessimistic but the fusion may be the only relief from pain at this point. I think many of the less-invasive options aren't available to you because of the previous diskectomy. However, from what I hear, the fusion technique has improved quite a bit even in the last 5 years, and the success rates are very high. Many people on these boards have gotten good results from fusions and had many pain free years.
Good luck and I hope this was helpful and not too depressing!
I wish you the very best, and freedom from pain.

Telzey
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4 years of back pain
Annular tear L5-S1 diagnosed 3/02 via MRI
IDET 12/2/02
Still a little sore, but getting better all the time!