Effect Of Lumbosacral Interbody Fusion For Lumbar Disorders On Adjacent Segment Degeneration

Objective:A retrospective study was conducted to investigate data of lumbar fusion length, lumbosacral angle who underwent lumbar interbody fusion. And to investigate the impact on adjacent segment degeneration after lumbosacral interbody fusion for lumbar disorders.Methods:A total of 120 patients who had undergone lumbar interbody fusion for the treatment of lumbar diorders at our hospital between January 2010 and June 2014 were retrospectively reviewed by chart review and telephone survey. According to the number of lumbar fusion segments, those patients were divided into two groups. Group A was L4/5 single segment fusion and L5/S1 segmental decompression or not(46 cases). Group B was L4/5 and L5/S1 double segments fusion(74 cases). The postoperative average follow-up time for the patients was one year. The Japanese Orthopaedic Association (JOA) score and Oswestry Disability Index (ODI) were used to evaluate the clinical symptoms. The University of California at LosAngeles Grading Seale(UCLA) system were used to evaluate adjacent segment degeneration on radiograph.Results:First, among the 120 patients,32.6% showed degenerative changes at group A and 47.2% showed degenerative changes at group B after surgery, there were statistically significant differences in the two groups (P<0.05).2.1% showed clinical symptoms at group A and 2.7% showed clinical symptoms at group B after surgery, there were no significant differences in the two groups (P> 0.05). In group A and B, the incidence of ASDeg and ASDis there were significant differences (P<0.05). Second, in the group A,21.7%(10/46) showed degenerative changes at L3/4 segment, 10.8% (5/46) showed degenerative changes at L5/S1 segment. The incidence of ASDeg between the two,there were significant differences (P<0.05).Third, in group A and B, the score of JOA and the Oswestry Disability Index in the final follow-up there a statistically significant difference compared with the preoperation. In the final follow-up, the Oswestry Disability Index in group A and B had significant difference (P<0.05); The score of JOA in group A and B had no significant difference (P> 0.05). Fourth, in group A and B, there were statistically significant differences in the angle of sacral inclination(P<0.05).Conclusion:The cranial segment has a higher degeneration risk than the caudal segment after lumbar interbody fusion. There was a trend of more ASDeg after long-segment fusion than short-segment fusion. And a hinger sacral inclination may be associated with the rate of ASDeg after lumbosacral interbody fusion. If L5/S1 has degenerative appearance and has chance to be the adjacent segment, but there is no evidence of obvious clinical symptoms, L5/S1 shouldn’t fused. During instrumented lumbar fusion, long-segment fusion should be avoided if possible.