Sagittal Balance Characteristics Of The Spine And Its Degenerated Evolution In Patients With Degenerative Lumbar Spondylolisthesis:A Clinical Study

Objectives:To compare the sagittal spine-pelvis parameters of patients with degenerative lumbar spondylolisthesis and patients with lumbar spinal stenosis,and analyze the correlation of spine-pelvic parameters.To analyze the characteristics of sagittal spinepelvis balance and the degenerated evolution pathway in patients with degenerative lumbar spine based on Roussouly classification.Methods:The patients with lumbar spondylolisthesis and lumbar spinal stenosis with complete imaging data were analyzed retrospectively.The following parameters were measured and recorded on the lateral X-ray films of the full spine using the in-hospital picture archiving and communication systems(PACS):pelvic incidence(PI),sacral slope(SS),pelvic tilt(PT),lumbosacral transitional vertebrae,the apex of lumbar lordosis(L-apex),inflection point of thoracolumbar curve,lumbar lordosis(LL),the apex of thoracic kyphosis(T-apex),thoracic kyphosis(TK),sagittal vertical axis(SVA),C7 Barrey ratio.Based on the type of disease,describe the characteristics of the spinepelvic parameters of two diseases,compare and analyze the sagittal pelvis and spine differences between the two groups of patients,and analyze the correlation between the parameters.Based on sacral slope,spine morphology,as well as pelvic tilt,the sagittal spine of patients was divided into four categories:classic Roussouly types 1-4,anteverted types(PT<5°),retroverted types(PT>25°)and special types.The effects of gender and disease on spine and pelvic morphology were analyzed separately.The lumbar spondylolisthesis cases were grouped according to whether they had isthmic fissure or not,to further compare whether there were differences in the sagittal spine-pelvic parameters between isthmic lumbar spondylolisthesis patients and degenerative lumbar spondylolisthesis patients,and compared with the spine-pelvic parameters of isthmic lumbar spondylolisthesis patients aged 18-35 years.Results:116 cases of lumbar spondylolisthesis(23 males and 93 females),107 cases of lumbar spinal stenosis(61 males and 46 females)and 30 cases of young isthmic spondylolisthesis were included.The PI,SS,PT,and LL in the lumbar spondylolisthesis group were significantly greater than those in the lumbar spinal stenosis group.The ratio of lumbosacral transitional vertebrae in patients with lumbar spondylolisthesis was also significantly higher than that in patients with lumbar spinal stenosis(15.5%vs 3.7%).There were significant correlations between pelvic parameters.PI,SS were significantly correlated with LL,and their correlation coefficients were 0.602 and 0.863,respectively,and TK was significantly correlated with LL(r=0.511,P<0.01).The distribution of spinal shapes classification in lumbar spondylolisthesis group:Classic Roussouly types 1-4 represented the majority in this group(6.0%,10.3%,30.2%and 25.0%,respectively).Anteverted types made the lowest incidence(3.5%)of the group.Retroverted types accounted for 18.1%of the group.Special types accounted for 6.9%of the group.Lumbar spinal stenosis group:classic Roussouly types 1-4 also made the most common category of this group,the percentages were:7.5%,30.8%,28.0%and 6.5%,respectively.Anteverted types accounted for 9.3%of this group.And retroverted types only accounted for 7.5%of the group.While special types accounted for 10.3%of the group.All subtypes of retroverted pelvis have high PI.There were no significant differences in sagittal spine-pelvic parameters and spine morphology between patients with isthmic spondylolisthesis and degenerative spondylolisthesis over 35 years of age.Patients with isthmic spondylolisthesis over 35 years of age had significantly different spine-pelvic parameters:PI,LL,TK,PT,SFD,and different spine morphology typing than those between 18 and 35 years of age.In addition,a special sagittal spine morphology,which is characterized by global thoracolumbar lordosis,was identified—the arch type in several patients with lumbar spondylolisthesis.Conclusions:This study confirms the greater PI,PT,SS,and LL in patients with degenerative lumbar spondylolisthesis.There are closely correlations between adjacent segments:the LL depends on SS and is highly correlated with TK.The rate of sacrum lumbarization is higher in patients with lumbar spondylolisthesis,which may be one of the risk factors for lumbar spondylolisthesis.And the sagittal spine morphology of female patients with lumbar spondylolisthesis are dominated by classic Roussouly types 3 and 4 and retroverted types with high PI values.The present study is the first to report the presence of retroverted types 1 and 4 and anteverted types 1 and 2 based on the Roussouly degenerative spine classification.This study shows that isthmic spondylolisthesis and degenerative spondylolisthesis over 35 years of age share a common feature,high PI,and both may simply be different stages of the same disease.The PI in young patients with isthmic spondylolisthesis is not large,and its etiology may be congenital isthmus dysplasia.PI is a marker to identify previous spine morphology,by which we can describe the possible evolution pathway of the spine from normal to degenerative morphology.