Biomechanical Analysis And Clinical Evaluation Of Cortical Bone Trajectory Screws In Lumbar Surgery

Part ? Finite element method analysis of biomechanical characteristics of cortical bone trajectory screws in lumbar surgeryObjective: To compare the fixation strength and biomechanical stability of cortical bone channel screw and pedicle screw in lumbar surgery by finite element method,and analyze the stress distribution of intervertebral disc and screws.Methods: Collecting the CT images of the lumbar spine of an elderly man with osteoporosis admitted to our hospital,and then the l3-l5 lumbar finite element model was established by threedimensional finite element technique.M1,M2 and M3 nailing methods were designed to simulate the operation of posterior lumbar fixation with four screws.In model M1,4 screws were fixed in traditional pedicle screw trajectory;model M2,4 screws were fixed in cortical bone trajectory;model M3,2 screws of left side were fixed in cortical bone trajectory,and 2 screws of right were fixed in traditional pedicle screw trajectory.To measure the motion of the lumbar spine in three different fixation methods,evaluate the stability of the lumbar spine after internal and postoperative surgery,calculate and analyze the stress intensity and stress distribution of intervertebral disc and screw.Results: In different activity states,the Range of motion in 3 fixed models were significantly reduced than that of the model without nailing.Among the three different fixed modes,the range of motion of M1 group was the largest,followed by M3 group and M2 group was the smallest.The stress of each disc in M1 group was the largest,followed by M3 group and M2 group.The maximum stress of each screw in three different fixation methods was significantly lower than the yield strength.The stress of each screw in M2 group was the largest,followed by M3 group and M2 group was the smallest.Conclusion:Cortical bone channel screws can improve the stability of the lumbar spine and reduce the load on the disc.Moreover,the screw can bear more stress and increase the fixed strength.Part ? Clinical efficacy and safety of cortical bone channel screws in lumbar surgery: a systematic review and Meta-analysisObjective: To compare the clinical efficacy and safety of cortical bone channel screw and pedicle screw in lumbar surgery with Meta-analysis.Methods: To search the All clinical study on the application of cortical bone channel screw and pedicle screw in lumbar surgery,which published from the date of inception to April 2019 in the Pub Med,Web of Science databases,EMBASE,Cochrane library,CNKI and the Wan Fang date.Two independent researchers carried out literature screening,literature quality evaluation and relevant data extraction.Then,the date analysis was conducted with Review Manager 5.3.Results: Twenty-five eligible studies were included,consisting of three randomized controlled studies and 22 cohort studies.A total of 1550 patients were included,consisting of 725 in the cortical bone channel screw group and 825 in the pedicle screw group.The analysis results showed that there was no significant difference in postoperative intervertebral fusion rate,secondary surgery rate,operation time,postoperative VAS score,JOA score and ODI score between the two groups(p > 0.01),and there were significant differences in intraoperative blood loss,mean hospital stay,postoperative drainage and incision length(p < 0.01).Conclusion: Compared with pedicle screws,cortical bone trajectory screws had similar effects in postoperative intervertebral fusion rate,secondary surgery rate,operation time,postoperative low back pain VAS score,postoperative leg pain VAS score,postoperative JOA score and postoperative ODI score.However,the intraoperative blood loss decreased,the average hospital stay shortened,the incision length decreased and the postoperative drainage decreased.