The Study And Related Risk Factor Analysis Of Adjacent Segment Degeneration Following One-level Lumbar Spinal Fusion

Objective：To observe the degenarative changes of the adjacent segment in patients whichhad been anderwent posterior lumbar fusion2years ago,and to investigate the impact ofthese changes and their causes.Methods： A total60patients who anderwent L4/5or L5/S1posterior lumbar fusion(PLIF or TLIF)during2009to2011were enrolled to investigate the degenerative changesof the adjacent segment(L3/4or L4/5or L5/S1) through their X-ray film and MRI.Theywere divided into group A (L4/5fusion) of44cases and group B (L5/S1fusion) of16cases according to the fusion section.According to the fusion technique, they were dividedinto PLIF (47cases) and TLIF group (13cases).The follow-up time ranged from24～36months(average，23.9months).The visual analog scale(VAS),Japanese OrthopaedicAssociation(JOA） and ASD were evaluated.The final X-ray and MRI were used to assessthe incidence of adjacent segment degeneration and degree.Results： The cranial degeneration of adjacent segment to fixed lumbar segment wasabserved in15.9%（7/44）in group Aand18.8%（3/16) in group B,respectively.The caudaldegeneration of adjacent segment was abserved in6.8%(3/44) in group A.The cranialdegeneration of adjacent segment to fixed lumbar segment was abserved in17.0%（8/47）in group PLIF and15.4%(2/13) in group TLIF,respectively.The JOA scores of all patientswere obviously improved after operation.But there was no correlation between the JOAscore and the adjacent segment degeneration.Conclusion： The cranial incidence of ASD has a higher risk than thecaudal,s.Floating fusion does not increase the risk ofASD.