Analysis Of Risk Factors Of Cage Subsidence Following Transforaminal Lumbar Interbody Fusion

ObjectiveAnalyse risk factors of patients with Cage Subsidence following transforaminal lumbar interbody fusion.MethodsA retrospective analysis was performed on patients who underwent single or double level transforaminal lumbar interbody fusion due to lumbar degenerative diseases such as lumbar spinal stenosis or lumbar instability in the Third Affiliated Hospital of Guangzhou Medical University from January 2020 to January 2022.Patient data were collected,including age,gender,body mass index(BMI),preoperative endplate Modic classification,preoperative L1 lumbar vertebral CT value,fusion segment,cage height,cage location,disc height before and after surgery,lumbar lordosis before and after surgery,and surgical method(minimally invasive/open).Patients included in the study were divided into cage subsidence(CS)group and the non-cage subsidence(N-CS)group according to whether disc space height difference>2mm between the last postoperative follow-up and the second postoperative day.Single factor analysis between the above groups was conducted to compare whether the above factors had statistical differences,and the factors with statistical differences were included in the Logistic regression.ResultsA total of 102 patients and 137 fusion levels were included in this study,in which 54 levels occured cage subsidence,with an incidence of 39.4%.Univariate analysis showed that there were statistically significant differences in age,cage height,cage location,endplate Modic classification,preoperative disc space height,surgical method and preoperative L1 lumbar vertebral CT values between the two groups(P < 0.05).Through multivariate Logistic regression analysis of the above factors,we reveal that posterior cage position(OR=3.230,95%CI: 1.074-9.715),open surgery(OR=0.117,95%CI: 0.026-0.526),low preoperative disc height(OR=0.719,95%CI: 0.548-0.944),low preoperative lumbar vertebral CT value(OR=0.950,95%CI: 0.927-0.973),endplate Modic Type I(OR=8.245,95%CI: 1.486-45.755),endplate Modic type II(OR=11.648,95%CI:2.683-50.569)were independent risk factors of cage subsidence following transforaminal lumbar interbody fusion.Conclusions1.The independent risk factors of cage subsidence of transforaminal lumbar interbody fusion are preoperative L1 lumbar vertebral CT value less than 118 HUs,preoperative disc height less than 8.775 mm,posterior fusion cage position,endplate Modic Type Ⅰ and type Ⅱ.2.The selection of minimally invasive transforaminal lumbar interbody fusion can effectively reduce the rate of the cage subsidence.