You have a disc herniation at L5-S1 below your fusion of L3-L5. Since your back pain never improved after surgery, it is unlikely that this new herniation is causing your current back pain. However, if the L5-S1 disc was degenerative prior to your fusion surgery above and was not suspected of causing pain, there is a possibility that is was also a pain generator but was not recognized as such.
Did you have a surgical work-up prior to your surgery for back pain? Did you have discograms or epidurals. If so, what were the results?
If you have a herniated disc at L5-S1, this could be causing your leg pain (assuming that you had no leg pain prior to the fusion surgery and the disc herniation occurred subsequent to the fusion surgery).
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.