The Study Of Associations Between Facet Sagital Angel With Its Tropism And Degenerative Lumbar Scoliosis

Background: Degenerative lumbar scoliosis is a common kind of spinal deformity in clinic.Vertebral rotatory subluxation(VRS)is a common kind ofimage manifestations in degenerative scoliosis.VRS have been not only found in association with the severity of symptoms in patients with degenerative scoliosis,but it was also regarded as a predisposing factor for curve progression of degenerative scoliosis.Although several risk factors of VRS,including age and Cobb angle,have been investigated,few studies focused on the correlation between VRS and anatomical structures of facet joints.Objective: This study aims to investigate facet sagital angel,its tropism in degenerative lumbar scoliosis,and evaluate the association between tropism of facet sagital angel and VRS.Methods and Materials Lumbar multi-slice helical computed tomogmphy(MSCT)images and plain radiographs of 64 inpatients with degenerative lumbar scoliosis and 64 inpatients with lumbar stenosis were reviewed.The lateral translation on coronal radiographs more than 5 mm and grade I(Nash-Moe classfication)vertebra rotation was defined as VRS.Multi-slice helical computed tomographic scans were made for all lumbar levels to measure facet sagital angel(FSA).The difference between right and left FSA was recorded as ?FA.Facet tropism was defined as ?FA more than 10°.Results In LDS group,FSA at the convex side is significantly less than the concave side at L3-L4 and L4-L5 levels(P < 0.05),while no significant difference was shown in FSA between the concave side and the convex side at L1-L2 and L2-L3 levels(P>0.05).In control group,no significant difference was shown in FSA between the concave side and the convex side at each lumbar level(P>0.05).The number of FSA tropism in LDS group was more than in control group significantly(P>0.05), and it is more focused at L3-L4 and L4-L5 levels.LDS group have a total of 79 VRS levels,it is most commonly found at the L3–L4 level(45)and,with decreasing frequency at L2–L3(21),L4–L5(11),and L1–L2(2).Based on FSA tropism and VRS are high incidence at L3-L4 and L4-L5 levels in DLS group,We further analyze the characteristics of the FSA at the VRS levels.In LDS group,FSA at the convex side were more coronally oriented compared with that at the concave side in levels with VRS,but no significant difference was shown in levels without VRS.?FA was also significantly different between levels with and without VRS(P < 0.05).In addition,?FA were found to be significantly associated with VRS by peaarson analysis(P<0.05,r=0.28).Tropism of facet sagital angle are risk factors for VRS using binary logistic regression analysis,with an odds ratio of 1.49.Conclusion: 1.Tropism of facet sagital angle is more significantly observed in degenerative lumbar scoliosis,and it is found in levels with VRS.2.The facet sagital angle at the convex side were more coronally oriented compared with that at the concave side at levels with VRS in degenerative lumbar scoliosis.3.Tropism of facet sagital angle is one of related risk factor of VRS in degenerative lumbar scoliosis that the more severe tropism in degenerative scoliosis,the greater the chance of VRS.