The Relationship Between The Short-term Changes Of Lumbar Sagittal Parameters And Cage Subsidence After Single Level Posterior Lumbar Interbody Fusion

Background and Objective:Lumbar interbody fusion,as an important clinical treatment in spinal surgery,has been widely used after a long time of development and progress,and has a real objective therapeutic effect.However,the accompanying sedimentation of the interbody fusion apparatus may indirectly affect the surgical effect.The sedimentation of the interbody fusion apparatus refers to the phenomenon that the height of the interbody space decreases at the surgical level after spinal fusion surgery,and the subsidence of the fusion apparatus into the vertebral body,which may lead to the loss of the effect of spinal canal decompression or interbody non-fusion and other adverse consequences.The research and exploration on the causes and countermeasures of fusion tank subsidence continue to expand,but there are still great controversies.Biomechanical factors are one of the important factors causing fusion cage sedimentation,and sagittal plane parameters of lumbar spine are closely related to spinal biomechanics.In order to further clarify the relationship between fusion fusion and sagittal parameters of lumbar spine,this study retrospectively analyzed 80 cases of single posterior lumbar interbody fusion,aiming to evaluate the short-term postoperative impact of fusion fusion on sagittal parameters of lumbar spine and explore the relationship between the two.Method:Eighty patients who received single-level posterior lumbar interbody fusion and underwent surgical treatment in China-Japan Union Hospital of Jilin University from January 2019 to January 2022 were selected as the research objects.A retrospective analysis was conducted based on clinical medical records,and the classification was made according to the decline of disc height(DH)at the last follow-up.It is divided into 4 levels:0,the decrease degree is less than 25%;Grade I,25%≤ decrease degree <50%;Grade Ⅱ,50%≤ decrease degree < 75%;Grade Ⅲ,75% ≤ decline≤100%.lumbar lumbar spine(LL)and segmental lordosis(SL)value,and segmental lordosis(LL)value,and segcobb angle,and pelvic tilt(PT),and pelvic incidence(PI),etc.before and after operation were compared and lumbar spine were followed up for 3-24 months.To analyze the factors related to fusion device settling and its influence on sagittal balance of lumbar spine.The measurement results were analyzed using SPSS 19.0 software as a statistical tool,and P<0.05 was considered to be statistically significant,which is used as a standard.Results:In this group,46 cases of grade 0 settlement,34 cases of grade Ⅰsettlement,no grade Ⅱ settlement,grade Ⅲ settlement.Compared with the 0 grade subsidence group,the improvement values of DH and SL before and after operation in the Ⅰ grade subsidence group were significantly different(P<0.05),there was no significant difference in LL improvement before and after surgery(P > 0.05).The loss of DH,SL,LL and Cobb Angle at the last follow-up in class Ⅰ settlement group was significantly different from that in class 0 settlement group(P<0.05).The improved DH value before and after surgery and the second life value after surgery are the risk factors of fusion device subsidence,which can significantly affect the sagittal balance of lumbar spine.Conclusion:1.There is no obvious relationship between the occurrence of interbody fusion cage settlement and gender,age and surgical segment.2.The intraoperative operation of lumbar fusion,especially the control of the improvement of SL and DH in the target segment of the intervertebral disc,can affect the occurrence of fusion cage settlement after surgery.Excessive increase of SL and DH height can promote the fusion cage settlement.It is recommended to refer to the preoperative data for reconstruction.3.Intervertebral fusion cage settlement can affect postoperative DH,LL and segmental Cobb angle,as well as PT and PI.This effect may not bring subjective symptoms in the short term.However,postoperative judgment of the surgical effect of patients can not only depend on the subjective symptoms of patients,but also focus on the changes in imaging.However,when there is abnormal change in sagittal balance,we should be alert to the aggravation of fusion cage settlement.