Risk Factors For Cage Retropulsion After Lumbar Interbody Fusion

Objective: This study was designed to identify risk factors for cage retropulsion(CR)after lumbar interbody fusion(LIF),and reduce the incidence of CR.Methods: From January 2018 to January 2019,326 patients who underwent LIF were enrolled.The information and radiographic data of patients were collected,and patients were classified into 2 groups according to CR.Eleven factors were analyzed in this study: gender,age,body mass index(BMI),preoperative diagnosis,adult degenerative scoliosis(ADS),type of operation,segment of operation,multilevel fusion,cage insertion depth,pre-operation posterior disc height(PDH)and pear-shaped disc(PDH).Chi-square test and t-test were used to analysis those factors.For statistically significant factors,a multivariate logistic regression analysis was performed to identify independent risk factors for CR.Result: CR was detected in 9(2.8%)of 326 patients.Statistical outcomes suggested that PSD(OR=7.431,P=0.010),insufficient depth of cage insertion(OR=9.161,P=0.015),ADS(OR=4.812,P=0.043)were independent risk factors for CR.However,gender,age,BMI,preoperative diagnosis,type of operation,segment of operation,multilevel fusion,pre-operation higher PDH are not the risk factors associated with CR.Conclusion: PSD,insufficient depth of cage insertion,ADS are independent risk factors related to CR.For patients with high risk factors,a larger size cage or double cages should be used and inserting the cage into the anterior location.For those who suffer from typical neurological symptoms,a revision surgery is needed.