The Analysis Of Influence Factors Of L5-S1Degeneration After Lumbar Floating Fusion

To investigate the influence factors for L5-S1segment degenerationafter lumbar posterolateral floating fusions.【Method】We investigated data from176patients who underwent lumbar posterolateral floating fusions by restrospectiveclinical study.The follow-up was43.3months(14to90).Among these patients,72underwent L4-5fusion,66L3-5and38L2-5fusions.They were divided into3groupsaccording to the number of segments.UCLA (University of California at LosAngelesGrading Seale) classification was used to evaluate the pre-and postoperativeradiographic results of the L5-S1segment.The risk factors that may influence thedegenerative changes at the L5-S1after surgery were analyzed by statistics.【Result】Among the176patients,54showed degenerative changes at L5-S1after surgery.Theoverall incidence of degeneration was30.7%.The degeneration at L5-S1occurred in22.2%(L4-5fusion),33.3%(L3-5fusions),42.1%(L2-5fusions).There were nostatistically significant difference in sex,age distribution or amount of follow-upbetween the degenerative and the normal patients(P>0.05).The rate of degeneration insingle level fusion (L4-5) was22.2%which differred significantly from that inmutilsegment fusions,36.5%after floating fusion surgery(P<0.05).The degenerationgroup had a higher angle of sacral inclination campared with the normal group(41.3±10.9°vs.32.4±10.6°in L4-5fusion group,39.9±9.8°vs.33.3±7.4°in L3-5fusion group).Among the176patients,2needed secondary operation because ofL5-S1ASD.【Conclusion】The degeneration at L5-S1could be found frequently afterlumbar floating fusions surgery.The number of fusion segments and a higher of sacralinclination may be associated with the rate of degeneration at L5-S1.