There is too little information to comment on the need for a fusion. I assume you have pars fractures at L5-S1 with a 2mm slip and a normal looking disc on MRI, that is the situation. Correct?
I then have to assume that you have completed a full rehabilitation program and failed. Have you undergone diagnostic and therapeutic injections that pointed to the pars fractures?
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.