Spinal Fusion, Degenerative Changes, and Clinical Outcomes Are Linked
There's always a concern after spinal fusion about the segment next to the fusion. Will it hold up? Or will there be increased load at that level causing breakdown? Studies have shown changes observed on X-rays after fusion. Disc degeneration, arthritis of the facet (spinal) joints, and instability can be seen.

But do X-ray changes correlate with clinical outcomes? In other words, do patients with adjacent segment degeneration (ASD) have decreased function as a result of the changes? That's the focus of this study from Korea.

Three groups of patients were evaluated by X-rays before fusion, after, and later at the end of two years. Group one had a fusion at one level. Group two had a fusion at two levels. And group three had more than three segments fused.

All fusions were done with the same posterolateral approach. This means the incision was done from the back and side of the spine. Screws and autogenousbone graft (bone harvested from the patient) were used to do the fusion. Outcome measures included pain, need for pain relievers or other drugs, activity level, and work status.

The results showed ASD in all three groups. The number of patients affected increased as the number of segments fused increased. Pain increased and function declined in all three groups. But the greatest change occurred in the group with the most levels fused. They had the worst clinical outcomes.

The authors confirm the belief that ASD does occur after spinal fusion. The worst cases occur in patients with multiple segment fusion. And function does decline when these changes are severe.

Surgeons must consider whether or not to include a spinal segment in the fusion when there are already degenerative changes present. Fusing more levels is not always the best answer. Clinical outcomes are directly linked to degenerative changes after fusion. This conclusion points to the need for better fusion methods or choosing disc replacement over fusion as the treatment choice.
Jun Young Yang, MD, PhD, et al. The Impact of Adjacent Segment Degeneration on the Clinical Outcome After Lumbar Spinal Fusion. In Spine. March 1, 2008. Vol. 33. No. 5. Pp. 503-507.