Q: If artificial disc replacements are available now, why do surgeons continue doing spinal fusions instead?

A: For a very long time, spinal fusion was the answer to chronic low back pain. But with time, surgeons were also able to see that once the spine was fused, load transferred to the next segment caused degeneration there as well. They call this phenomenon: adjacent segment degeneration (ASD). Many solutions to the problem of ASD have been proposed.

The use of artificial disc replacement has been one way to approach the problem. The hope is to preserve spinal motion while protecting the adjacent vertebral levels. But when comparing the results between spinal fusion and disc replacement, there hasn't been an overwhelming benefit shown for disc replacement over spinal fusion.

For that reason, some surgeons continue to look for ways to improve results of spinal fusion. They have tried different fusion techniques. They have analyzed patient factors looking for ways to identify patients who would benefit the most from spinal fusion. Factors of both patient (age, body mass index, lifestyle) and procedure (number of levels fused at one time, use of hardware to assist fusion, surgical errors) remain under investigation.

And some people just aren't a good candidate for disc replacement. Spinal fusion may be the only reasonable choice for them. The uses of disc replacement are expanding and may eventually include all patients with chronic low back pain from disc disease. But for now, surgeons select patients carefully in an effort to prevent complications and assure success.

Reference: Tina S. Videbaek, MD, et al. Adjacent Segment Degeneration After Lumbar Spinal Fusion: The Impact of Anterior Column Support. In Spine. October 15, 2010. Vol. 35A. No. 22. Pp. 1955-1964.