I am confused. Lower back pain is typically generated by the discs and facets, not the nerve roots. Your surgeon decompressed the nerve but did not stabilize the vertebral segments (fusion) due to your “smoking”. The surgeon then repeated the X-rays and noted “she could see a further slippage on the L5 which is why my leg pain has probably come back”.
“Further slippage” to me means continued instability of this motion segment. This very likely could be the source of your back pain. In addition, return of your leg pain more likely than not means that this continued slip has caused further foraminal stenosis which could be the source of your leg pain.
It might be valuable to get another set of eyes to look at your images and perform a thorough evaluation. Find an experienced spine surgeon who will take the time with you.
Dr. Corenman
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.