Imaging Analysis For Occurrence Of Adjacent Segment Degeneration After Lumber Fusion For Degenerative Lumbar Spine Disease

Objective To investigate the factors affecting the occurrence of adjacent segment degeneration after lumbar fusion by analyzing the imaging changes of adjacent segment.Methods:The clinical data of188patients with degenerative lumbar spine disease who underwent posterior lumbar surgery between1st January2009and31st December2103were collected and retrospectively analyzed. The disc height of the adjacent segment, angle between the adjacent discs and translational distance were measured in the post-fusion X-ray films. The patients were divided into degenerative group (group A) and non-degenerative group (group B) according to the image at the last follow-up, and the difference in age between the two groups were analyzed. The patients in group A were divided into single segment group (group A1), double segments group (group A2) and triple or more segments group (group A3) according to the length of fixation and fusion, and the difference in time of adjacent segment degeneration incidence among the3groups were analyzed. For patients with both upper and lower adjacent segments degeneration in group A, the incidence of upper adjacent segment degeneration and lower adjacent segment degeneration were calculated respectively.Results:81patients (43%) had adjacent segment degeneration at last follow-up. The difference in age between group A and group B was statistically significant (P<0.05).Group A1, A2and A3showed significant difference in average period for adjacent segment degeneration incidence (P<0.05). All the patients in group A had upper adjacent segment degeneration (100%),46cases (57%) had both upper and lower adjacent segments degeneration, among which29cases (63%) had lower adjacent segments degeneration.Conclusions:Age is the vital factor that would affect the occurrence of adjacent segment degeneration after lumbar fusion, with higher incidence observed in patients with higher age. The increase of the length of fusion might promote the occurrence of adjacent segment degeneration and upper adjacent segment hsa higher incidence of degeneration when compared to lower adjacent segment.