The impact of adjacent segment degeneration on the clinical outcome after lumbar spinal fusion

Abstract

Study design: A retrospective study.

Objective: To determine the impact of the adjacent segment degeneration (ASD) on the clinical outcome after lumbar fusion.

Summary of background data: Few studies have analyzed correlation between clinical outcomes and ASD.

Methods: From January 2000 to December 2004, 217 patients who underwent lumbar fusion and have more than 2 years of follow-up were evaluated. The patients were divided into 3 groups: fusion was carried out on 1 (A), 2 (B), and more than 3 segments (C). UCLA grading scale was used to evaluate the ASD on radiograph preoperative, postoperative, and last follow-up. The clinical outcome was evaluated and the association between clinical outcome and ASD was evaluated by the Spearman correlation.

Results: ASD occurred 11.6% (13/112 cases) in group A, 14.5% (9/62 cases) in group B, and 16.3% (7/43 cases) in group C. Among them, the cases which had progressed more than 2 level of degenerative grade were 0 in group A, 7 cases (77.8%) in group B, and 6 cases (85.7%) in group C. In group A, 5 cases with ASD had down graded 1 level in clinical outcome. In group B, all 9 cases with ASD had down graded more than 1 level in clinical outcome; 1 level aggravation in 1, 2 level in 5, and 3 level in 1 case. In group C, all 7 cases with ASD also had down graded more than 1 level in clinical outcome; 1 level aggravation in 2, 2 level in 5 cases. Finally, the more the change of the degenerative grade is severe, the more the clinical outcome is worse (P < 0.05).

Conclusion: The impact of ASD on clinical outcome after fusion showed a significant correlation, especially with the ASD after multiple-segments fusion. Careful attention is needed in multiple-segments fusion such as degenerative lumbar deformity.