Risk of adjacent-segment disease requiring surgery after short lumbar fusion: results of the French Spine Surgery Society Series.

OBJECTIVE Adjacent-segment disease (ASD) is an increasingly problematic complication following lumbar fusion surgery. The purpose of the current study was to determine the risk of ASD requiring surgical treatment after short lumbar or lumbosacral fusion. Primary spinal disease and surgical factors associated with an increased risk of revision were also investigated. METHODS This was a retrospective cohort study using the French Spine Surgery Society clinical data that included 3338 patients, with an average follow-up duration of 7 years (range 4-10 years). Clinical ASD requiring surgery was the principal judgment criterion; the length of follow-up time and initial spinal disease were also recorded. Kaplan-Meier survival analysis was performed. The correlation between primary spinal disease and surgery with an increased risk of revision was investigated. RESULTS During the follow-up period, 186 patients required revision surgery for ASD (5.6%). The predicted risk of ASD requiring revision surgery was 1.7% (95% CI 1.3%-2.2%) at 2 years, 3.8% (95% CI 4.9%-6.7%) at 4 years, 5.7% (95% CI 4.9%-6.7%) at 6 years, and 9% (95% CI 8.7%-10.6%) at 8 years. Initial spinal disease affected the risk of ASD requiring surgery (p = 0.0003). The highest risk was observed for degenerative spondylolisthesis. CONCLUSIONS ASD requiring revision surgery was predicted in 5.6% of patients 7 years after index short lumbar spinal fusion in the French Spine Surgery Society retrospective series. An increased risk of ASD requiring revision surgery associated with initial spinal disease showed the significance of the influence of natural degenerative history on adjacent-segment pathology.