A Comparison of Adjacent Segment Diseases Above One Versus Above Two Vertebral Segment after Spinal Fusion of the Degenerative Lumbar Disease

ABSTRACT

STUDY DESIGN: Retrospective study. OBJECTIVE: To compare patients who underwent spinal revision surgery of adjacent segment degeneration with above one and above two vertebral segment preceded by initial spinal fusion surgery. SUMMARY OF LITERATURE REVIEW The adjacent segment disease(ASD) occurs more frequently at the more proximal segment of the spinal fusion. Also, the preexisting degenerative segments (with discs or facet joints) not included in the fusion procedure, fusion segmental sagittal angle, fixed appliances method, gender, and age, have been accepted as the causes. MATERIALS AND METHODS: The patients were watched over a year after the spinal revision operation followed by initial spinal fusion of single or multiple segments; the subjects were limited to 41 patients. The average age, entity of diseases, average duration between the initial spinal fusion and the revision surgery, multiple clinical and radiographic parameters were evaluated and compared. RESULTS: Using the UCLA grade of intervertebral disc degeneration, the average grade of 1 level upper segment was 2.2 in group A and 1.9 in group B without statistical significance(p=0.426). However, the average grade of 2-level upper segment was 1.8 in group A and 2.4 in group B with significant difference(p=0.021). There was no statistical difference in other factors between the two groups. CONCLUSIONS: Patients with ASD of above two-vertebral segment after spinal fusion were more severe in disc degeneration than those with ASD of above one vertebral segment before initial spinal fusions.