Risk Factors for Adjacent Segment Disease After Lumbar Fusion / 대한척추외과학회지

ABSTRACT

STUDY DESIGN: Retrospective study of adjacent segment disease. OBJECTIVES: To describe the incidence and clinical features of adjacent segment disease (ASD) after lumbar fusion and to determine its risk factors. SUMMARY OF LITERATURE REVIEW The reported incidence of adjacent segment problems is variable, and little has been discussed about surgically treated cases. Risk factors also have not been precisely identified, especially based on structural changes seen on magnetic resonance imaging (MRI). MATERIALS AND METHODS: We analyzed the records of 1,124 patients who underwent lumbar or lumbosacral instrumented fusions between August 1995 and March 2006 and had at least one year follow-up. Of these patients, 28 patients who needed secondary operations because of ASD were included in this study. The disease group was compared with an age-, sex-, fusion level-, and follow-up period-matched control group composed of the same number of patients, toward the purpose of analyzing six variables as risk factors. RESULTS: The incidence of ASD requiring surgical treatment was 2.48%. The mean patient age was 58.4 years, which showed no statistically significant difference from that of the population in which ASD did not develop (57.0 years, p=0.429). Only 1 distal ASD occurred among 21 floating fusions. Facet degeneration was a significant risk factor (p<0.01) on logistic regression analysis. CONCLUSION: Our study patients with ASD complained of severe symptoms with frequent neurological abnormalities. The incidence of distal ASD was much lower than that of proximal ASD. Pre-existing facet degeneration may confer a high risk of adjacent segment problems after lumbar fusion procedures.