Fusion is only necessary if there is instability of the segment present or the major complaint is lower back pain and not buttocks and leg pain. The other indication for fusion is a collapse of the foramen (the exit zone of the nerve root) where further decompression will only lead to further collapse. In this case, a fusion is necessary to open up this hole and prevent further collapse.
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.