Relationship Between Lumbar Curvature And Adjacent Intervertebral Space Changes After TLIF

ObjectiveTo analyze the relationship between lumbar curvature and degenerative changes of adjacent intervertebral space for patients receiving Transforaminal Lumbar Interbody Fusion(TLIF)due to lumbar degenerative diseases.MethodsFrom January 2017 to December 2017,247 patients received TLIF due to lumbar degenerative diseases were retrospectively analyzed.All the patients treated by the same surgeon,who are followed by 36 months on average(28-42 months).After selection,97 patients with complete follow-up data met the inclusion criteria,enduring low back pain and lower limb radiculopathy before the operation.Perioperative records were retrieved(gender,smoking history,age,body mass index),Pelvic Incidence(PI)and Sacral Slope(SS)were measured.Lumbar Lordosis(LL),Lumbar Lordotic index,intervertebral height of adjacent segments and motion angle and horizontal displacement distance of intervertebral space in sagittal plane were measured at three different periods:pre-operation,immediately post-operation and at the last follow-up.Patients were divided into group A(adjacent intervertebral space change group)and group B(adjacent intervertebral space normal group)based on degenerative changes of adjacent segment intervertebral space at the last follow-up,such as more than 3mm of the loss of height or the sagittal displacement,or the angular movement on sagittal space exceeding11°.Moreover,patients were further divided into group C,group D,group E based on the change between postoperative and preoperative lumbar lordosis.Respectively unreduced group,reduced less than 10°group and reduced more than 10°group.Finally,patients were subdivided into single-segment group and multi-segment group(≥ 2segments)based on the number of segments being operated.The relationship between the lumbar curvature and the number of operation segments after TLIF was analyzed statistically.Results18 patients showed degenerative changes at adjacent intervertebral space at the last follow-up,with the incidence of degenerative changes after TLIF being 18.56%.There was no significant difference in gender,smoking history,age,body mass index and radiographic indexes between the two groups(P > 0.05).There was significant difference in lumbar lordosis angle,lumbar lordosis index and lumbar curvature between the two groups(P < 0.05).Significant differences were found among the three groups comparing the LL after-operation,the more postoperative lumbar lordosis loss,the higher the incidence of adjacent segment vertebral space changes(P < 0.05).Besides,significant difference was found among the two groups about segment,the incidence of adjacent segment vertebral space changes after muti-segment TLIF was higher than single-segment TLIF(P < 0.05).ConclusionPostoperative lumbar curvature,lumbar lordosis angle and lumbar lordosis index may be related to the change of adjacent intervertebral space.The more the curvature of lumbar vertebrae decreased after operation,the more likely the adjacent intervertebral space changed after operation.The incidence of degenerative changes of multi-segment TLIF is higher than single-segment TLIF.Much attention should be paid to restore the lumbar curvature and prevent the loss of the lumbar curvature during the operation in order to lower the occurrence of adjacent segment intervertebral height loss.