Analysis Of Risk Factors For Failure Of Spinal Internal Fixation Systems

ObjectiveTo investigate the risk factors associated with failure of spinal internal fixation systems.MethodsA retrospective analysis of 89 patients with internal fixation failure and 4262 patients with spinal fixation was performed from May 2012 to February 2019.In spinal internal fixation group the age and gender were statistically analyzed.Survival analysis and correlation analysis of the internal fixation failure group of existing parameters such as age,gender,height,weight,BMI,disease,time of internal fixation failure,number of vertebral the internal fixation spans,number of actual fixation vertebral,total number of screws,total number of screw,the number of internal fixation implants,the total number of internal fixation implants outside the screw,the use cross-linkage or not,the number of cross-linkage,the type of internal fixation,the single or double-sided internal fixation.And survival analysis and correlation analysis of the calculated parameters such as the relative density of screws,the absolute density of screws,the relative density of attachments,the relative density of attachments,the relative density of total implants,the absolute density of total implants.Results There was a statistically significant difference in the age between the internal fixation failure group and spinal internal fixation group(P<0.001).The age of the former was significantly smaller than the latter.There was no significant difference in gender composition.The time to failure in the internal fixation failure group was significantly weakly correlated with age(r=-0.221,P=0.038)and was not significantly associated with BMI.Patients with obesity(BMI>27.0 kg/m~2)in the internal fixation failure group had significantly higher risk of internal fixation failure than non-obese patients(HR=2.586,P=0.037,95%CI:1.060-6.308).Among the adult patients who were fixed double-sided with the pedicle screw internal fixation system,the risk of internal fixation failure was significantly higher in patients with cross-linkage than in patients without cross-linkage(HR=2.652,P=0.021,95%CI:1.161-6.058).Correlation analysis was conducted on time of internal fixation failure for different internal fixation types.In the pedicle screw internal fixation system group,there was a significant low correlation between the time of failure and the number of number of actual fixation vertebral(r=-0.319),the total number of internal fixation implants(r=-0.328).In the titanium cage titanium plate fixation system group,there was a significant moderate correlation between the time of failure and absolute density of the screws(r=0.484),the absolute density of the total implant(r=0.515).In the occipitocervical fusion system group,there was a significant height correlation between the time of failure and the relative density of the screw(r=-0.841),the absolute density of the screw(r=-0.841),the relative density of the total implant(r=-0.880),the absolute density of the total implant(r=-0.841).In the co-analysis of the pedicle screw internal fixation system group+occipitocervical fusion system group+Harrington internal fixation system group,there was a significant low correlation between the time of failure and the total number of screws(r=-0.378),and there was a significant moderate correlation between the time of failure and the total internal fixation implant(r=-0.441).In other related analyses in the internal fixation failure group,the correlation between the failure time and BMI,number of vertebral the internal fixation spans,number of actual fixation vertebral,the total number of screws,the number of cross-linkage,the total number of attachments,the total number of internal fixation implants,the relative density of screws,the absolute density of screws,the relative density of attachments,the absolute density of attachments,the relative density of total implants,the absolute density of total implants were not significant(P>0.05).Conclusion The time of internal fixation failure may be related to the age of the patient,the number of implants,the implant density of implants and BMI.For adult patients who need to undergo titanium cage and plate fixation,increasing structural stiffness helps to delay the time of internal fixation failure.For adult patients who need to undergo the pedicle screw internal fixation,the surgeon should include the BMI in the surgical planning,use cross-linkage and double-sided internal fixation reasonably,to keep the balancing between stable benefits immediately after surgery and fixed failure risk in the long term.