Comparison Of Insertion Torque And Short-term Clinical Effect Of Penetrating S1 Endplate Screw,Tricortical Screw And Bicortical Screw

Objective To compare the insertion torque of penetrating S1 endplate screw,tricortical screw and bicortical screw and observe the short-term clinical efficacy.Methods 70 cases suffered from lumbosacral degeneration diseases or spondylolisthesis treated with lumbosacral segment instrumentation and decompression were admitted to 3 different groups from July 2018 to February 2021.Penetrating S₁upper endplate fixation,bicortical fixation and tricortical fixation of S₁pedicle screw were applicated in group A（n=25）,in group B（n=22）and in group C（n=23）.The gender,age,body mass index（BMI）,bone mineral density（BMD）and the visual analog scale（VAS）and Oswestry Disability Index（ODI）of preoperation and postoperation at 1,3,6,12months in the each three groups were recorded respectively.The maximum implanted torque of S1 screws with different technique,the length of the implanted screw（6.5mm in diameter）,the planting time of per S1 screw in each groups and intraoperative and postoperative complications associated with the implanted screw were recorded respectively.The rate of loosing screw,breakage of screw and the fusion（Suk criterion）during the follow-up,the VAS and ODI at 1,3 and 6 months and the last follow-up after surgery were evaluated respectively.Results All patients obtained follow-up ranged 3～12 months with a mean of 4.2±1.1 months.There was no statistical significance in gender,age,BMI,BMD,VAS and ODI among the three groups（P>0.05）.The maximum implanted torque of S1 screws were 2.55±0.66 N·m in group A,1.86±0.0.61N·m in group B,3.36+±0.62N·m in group C respectively.The implanted torque in group C was significantly higher than it in group A and in group B respectively and it in group A was higher than that in group B.Three groups were statistically significant（P<0.05）;The screw length in group C was significantly longer than it in group A and in group B respectively,there was no significant difference between group A and group B（P<0.05）.The VAS and ODI in group B is obviously higher than its in group A and C at 1 month and 3month after surgery respectively（P<0.05）,there was no statistically significant difference between its in group A and in group C（P>0.05）.The VAS and ODI in the three groups were improved compared with its before surgery in each group,and there was no significant difference among the three groups at the last follow-up（P<0.05）.There was no statistical difference about the intraoperative and postoperative complications associated with the implanted screw among the three groups.During the follow-up,there was 1 case in group A with loosing screw without broken screw or rod,7 cases with loosing screw and brokened screw in group B,and no case with screw fracture in group C.There was no statistically significant difference about rate of screw loosing and screw brokened between group A and group C（P>0.05）.There were statistically significant differences between group A and group B,and between group C and group B（P<0.05）;t There was 1 case in group A without fusion,7 cases without fusion in group B,and all patients in group C had bony fusion.There was no statistically significant difference about rate of screw loosing and screw brokened between group A and group C（P>0.05）Conclusion The clinical efficacy of the penetrating S1 endplate screw was comparable to that of the tricortical fixation and superior to that of the bicortical screw fixation.