Study On Patterns And A New Classification Of Spino-pelvic Sagittal Alignment In Adults

Objective:To establish a new classification of adult spino-pelvic sagittal alignment based on lumbar lordosis(LL)and thoracolumbar lumbar Inflection Point(TLIP)according to the correlations between spino-pelvic sagittal parameters measured in adult volunteers.Methods:Whole spine,standing radiographs of 111 volunteers were taken.The including criteria of volunteers:1,age:20 to 60 years old,2,no history of spinal and lower extremity joints disease,3,without a long history of low back pain,4,no vertebral deformity in X ray,mild vertebral wedge was regarded as normal Vertebral variation.A total of 56 women,55 males were included in this study.General parameters:age,weight,height.Parameters measured on x ray:TK(thoracic kyphosis),TLK(thoracolumbar kyphosis),LL(lumbar lordosis),SS(sacral slope),PT(pelvic tilt),PI(pelvic incidence),SVA(sagittal vertical axis),Intervertebral endplate Angle,SSA(spino-sacral Angle),Intervertebral endplate angle,thoracolumbar lumbar Inflection Point(TLIP,the inflection point between thoracic kyphosis and lumbar lordosis,the intervertebral space which Intervertebral endplate Angle absolute value closet to 0 °).Analyzed the correlations of the measured parameters by Pearson correlation coefficient test.According to LL and TLIP,the adult spine-pelvic sagittal alignment can beclassified into 3 types,and the parameters of type ? to ? were compared.Results:The mean±SD and ranges for each parameter were,Age 37.22 ± 10.77 years(20?60 years old),height 164.68 ± 7.72cm(144?186cm),weight 60.83 ± 10.83Kg(45?99Kg).(16.8 to 56.5°),TLK 6.40 ± 7.43°(-12.85 to 23.43°),LL-48.75 ±10.03 °(-68.6 to-21.2 °),SS 33.57 ± 7.64°(14.07 to 52.18(64.99?70.52),SVA-2.66 ± 22.79 mm(-65.81?44.73 mm),SSA 127.32 ± 8.98 °(106.25?153.42 °),L4L5-12.13 ± 3.01°(-18.51?-5.53 °),L3/L4-6.46 ± 2.33°(-13?0°),Intervertebral endplate Angle L5S1-11.82 ± 4.23°(-23.4?-2.3°)L4L5-12.13±3.01°(-18.51?-5.53°),L3/L4-6.46±2.33°(-13?0°),L2L3-3.51 ± 2.18°(-9.92?1.29°),L1L2-1.53±1.97°(-7.94?2.51°),T12L1 0.25±1.59°(-5.51?4.81°),T11T121.64±1.44°(-3.83?5.59°),T10T11 2.2±0.99°(-2.3?5.56°).TLIP L3/4 1 case,L2/318 cases,L1/2 13 cases,T12/L1 62 cases,T11/12 17 cases.Analysis of Pearson correlation coefficient test showed that only LL had significant statistical correlations with all the other parameters.Negative correlations presented between LL and TK,PI,SS,SSA,and r were-0.387?-0.536?-0.858?-0.801(P<0.01).While positive correlations presented between LL and TLK,SVA,PT,and r were 0.319?0.296?0.262(P<0.01).According to LL,TLIP can be divided into 3 types,type 1:LL>-40 °,TLIP is L2/3 or lower,type ?:-60 °<LL<-40 °,TLIP is L1/2 or T12/L1;type ?:LL<-60 °,TLIP is T11/12 or upper.All the volunteers can be included in the classification:type ? 19 cases,type ? 75 cases,type ? 17 cases.The LSD Multiple Comparisonsof LL,SS,SSA and PI between different classification types showed significant Statistical differences,P<0.05.There were significant correlations between LL and TK,PI,SS and SSA,and r were-0.387,-0.536,-0.858,-0.801(P<0.01),and TLK,SVA,PT were positively correlated,r were 0.319,0.296,0.262(P<0.01).According to LL,TLIP can be divided into 3 types,type 1:LL>-40°,TLIP is L2/3 or lower,type ?:-60 °<LL<-40 °,TLIP is L1/2 or T12/L1;type ?:LL<-60 °,TLIP is T11/12 or upper.All the volunteers can be included in the classification:type ? 19 cases,? type 75 cases,? type 17 cases.The LSD Multiple Comparison Between LL,SS,SSA and PI showed there were statstic differences between different classification types,P<0.05.Conclusion:The patterns of the spino-pelvic sagittal alignment were:the smaller LL angle,the smaller PI,the bigger TLK angle,the longer TK with smaller TK angle,the retroversion sacrum,the posterior superior corner of SI farther backward from femoral head,horizontal pelvis,the trunk leant forward,the spino-pelvic sagittal alignment trending positive unbalance,and vice versa.LL played a core role in the spino-pelvic sagittal balance.According to LL and TLIP,the spino-pelvic sagittal alignment can be classified into 3 types,and this classification can better reflect the balance in spino-pelvis sagittal alignment in adults.