Changes Of The Spinal-pelvic Parameters Associated With Second Alar Sacral Iliac Screws And Analysis Of Lumbosacral Complications

Objective:The changes and the risk factors of spine pelvic parameters on long-segments fusion patients associated with the second sacral alar iliac screws(S2AI)were analyzed,and analyze the incidence of lumbosacral complications in S2AI to evaluate its clinical efficacy compared to iliac screws.Methods:We retrospectively collect data of 34 patients who underwent S2AI or IS from January 1,2013 to April 30,2018,including general information(gender,age,body mass index BMI,Diagnosis),spinal pelvic parameters,lumbar lordosis,lumbosacral complications(implant failure,prominence of screws,acute infection,decubitus).S2AI patients were divided into two groups according to the change of PI in S2AI patients,group A were reduced by>5°,and group B were unchanged or increased or decreased by<5°,and candidates risk factors were selected according to professional knowledge.Age,BMI,preoperative PI,preoperative LL,preoperative PI-L,postoperative PI-LL postoperative LL change(preoperative LL-postoperative LL)and PI change values were analyzed by bivariate correlation.Significant factors associated with postoperative PI changes through bivariate correlation will be further analyzed by multivariate linear regression analysis to determine the risk factors for PI changes.The patients were divided into two groups:S2AI group and IS group to analyze the incidence of lumbosacral complications.Results:There were no significant differences in the general information between the S2AI group(n=21)and the IS(n=13)group except for the length of follow-up,P>0.05.The postoperative PI decreased by 3.58±3.92 in S2AI patients and 7.13±1.58 in group A(n=10),0.54± 2.31 in group B(n=11),P?0.0001.Bivariate correlation analysis show preoperative PI,preoperative PI-LL,and postoperative PI-LL were associated with PI reduction in postoperative patients,with correlation coefficients of 0.869,P<.05,0.80,P=0.001,0.573,P=0.041,respectively.Multivariate regression analysis showed that preoperative PI was associated with postoperative PI changes.The standard regression coefficient was 0.322,R2=0.828,P=0.012.The incidences of implant failure,prominence of screws,decubitus,acute infection in the S2AI and IS groups were 4.76%/12.50%,P=0.568,0.00%/25.00%,P=0.0272,4.76%/18.80%,P=0.296,9.52%/12.50%,P=1.000,respectively.Conclusion:Some patients who underwent S2AI had a reduced PI.Preoperative large PI was associated with reduction of PI in postoperative patients.Patients with S2AI have a lower incidence of implants prominence than IS.