Biomechanical And Clinical Study Of Percutaneous Endoscopic Lumbar Interbody Fusion

Part 1: Finite element analysis of lumbar interbody fusion under percutaneous endoscopyObjective: To establish lumbar degeneration model and simulate PE-TLIF and PE-PLIF models.To observe the stress distribution of fusion apparatus,endplate,internal fixation and vertebral body,and the interbody activity of fusion segment when the two models are added with the same posterior fixation,so as to provide a stress basis for PE-LIF clinical practice.Methods: The lumbar spine of male degenerative in Western China was collected and64 row spiral CT was scanned with 0.625 mm to obtain the complete lumbar CT data,and the model was constructed and verified and adjusted.Then,the PE-PLIF(model A)and PE-TLIF(model B)were simulated in the L4-5 segment,and the boundary conditions and loads were set up,and the final results were obtained by operation analysis.Results: 56373 units and 109872 nodes were found in the model of lumbar degeneration.The range of motion of flexion,extension,lateral bending and axial rotation were 0.61,0.43,0.73 and 0.57 in model A,4.47,4.70,3.37 and 5.78 in L3-4,0.49,0.42,0.72 and 0.64 in model B,and 4.33,4.62,3.28 and 5.52 in L3-4.In the two models,the maximum stress of the lower endplate was higher than that of the upper endplate,and the maximum stress of the endplate was 33.237 Mpa.The maximum stress of model A was 2.1:1,1:2.0,1.5:1,1.9:1,1.4:1 and 2.4:1,respectively,compared with model B.the maximum stress of model A was 1:1.7,1.2:1,1:1.2,1:1.5,1:1.3,1:2.3 and 1:1.8,respectively.In all the movements of the two models,the maximum stress produced by the left bending on the screw rod system was the highest,and the maximum stress produced by the forward bending on the vertebral body was the highest.In the two models,the maximum stress values of screw rod and vertebral body were similar,and the change trend was consistent.Conclusion: The finite element model of lumbar degeneration was established in this study.The results of the calculation are compared with the data of the cadaver model reported in the literature.The biomechanical study of degenerative lumbar spine can be carried out,and the advantages and disadvantages of various surgical schemes can be analyzed.Interbody fusion cage combined with pedicle screw can provide reliable immediate fixation for lumbar fusion,and the displacement and range of motion of the fixed segment are significantly reduced.The results of lumbar motion constraint of the two surgical models are similar.The stress of the lower endplate was higher than that of the upper endplate(lower than the yield stress of 138Mpa).Anteflection,lateral bending and rotation have great influence on cage,endplate,intervertebral displacement and range of motion.Model B may be more stable than model A and have less damage to the inferior endplate.Part 2 Comparative study of percutaneous endoscopic transforaminal and posterior lumbar interbody fusionObjective: To compare the imaging and short-term clinical results of PE-TLIF and PE-PLIF in the treatment of lumbar degenerative diseases based on finite element analysis.Methods: 29 patients with lumbar degenerative diseases were selected from January1,2019 to October 31,2020,and 29 patients were divided into PE-T group and PE-P group according to the operation method.The demographic data,imaging data,operation related indexes,clinical evaluation indexes and complications data of all patients were collected.The results were analyzed statistically.Results: Among 29 PE-LIF patients,22 cases in PE-P group and 7 in PE-T group,the difference was not statistically significant(P>0.05),and the number of spondylolisthesis in PE-P group was 15:1 than that in PE-T group(P=0.026).The operation time of PE-P group was shorter than that of PE-T group(t=6.541,P< 0.001).In PE-P group,the highest frequency of using fusion cage was 10 mm height(81.8%),and in PE-T group,85.7% was 8 mm height(U=17.000,P<0.001).The postoperative IDH of the two groups was higher than that before operation(t PE-P=7.464,P<0.001;t PE-T=6.173,P=0.001),and VLA was improved compared with that before operation(t=5.910,P<0.001).The Cobb angle was increased(t=5.617,P<0.001).There was no significant difference in the angle of IDH,VLA and Cobb between the groups(P>0.05).The length ratio of cage in PE-P group was higher than that of PE-T group(t=5.647,P<0.001),and the deviation angle of cage in PE-P group was significantly lower than that in PE-T group(t=32.146,P<0.001).VAS,JOA and ODI scores of the two groups were significantly improved(P<0.05),and there was no significant difference between the two groups(P>0.05).The total excellent and good rate of Macnab was 79.3%(23/29),and the complication rate was 10.3%(3/29).Conclusion: This study shows that PE-PLIF is more widely used in lumbar spondylolisthesis than PE-TLIF,which expands the surgical indications.Both methods can improve the fusion segment collapse(IDH),lumbar lordosis angle(VLA)and lumbar lordosis angle(Cobb angle).The effects of oblique placement of fusion cage on cage-endplate and screw rod fixation system are unclear.The clinical results of PE-PLIF and PE-TLIF were similar,which could improve the preoperative clinical symptoms.But PE-P group had shorter operation time,lower operation difficulty and shorter learning curve than PE-T group.Part 3.Comparative study of percutaneous endoscopic lumbar interbody fusion and open transforaminal lumbar interbody fusionObjective: Previous studies showed that there was no significant difference in imaging and clinical efficacy between the two PE-LIF techniques.In this part,we compared the changes of CK,CRP,blood loss and hidden blood loss between PE-LIF and open TLIF,as well as their impact on imaging indicators and short-term clinical efficacy,to further analyze whether PE-LIF has more advantages than open TLIF.Methods: Retrospective cohort study was adopted.Patients with lumbar degenerative diseases in the Department of orthopedics,Affiliated hospital of Chengdu University of TCM from January 1,2017 to October 31,2020 were selected and divided into PE group and OPEN group according to the operation method.The end point of follow-up was February 28,2021.Demographic and imaging data such as gender,age,height and weight of all patients were collected.The course of disease,incision length,operation time,intraoperative fluoroscopy,blood loss,drainage volume,postoperative hospital stay,related complications,fusion rate,and Mac Nab were recorded,as well as laboratory results such as HCT,CRP,CK value at each time point,VAS score,JOA score and improved ODI and statistical analysis.Results: Based on the average and standard deviation of CK,CRP and blood loss,the sample size was calculated.The minimum sample size of each group was 22 cases of CK,24 cases of CRP and 21 cases of blood loss.Considering the shedding rate of10%-20%,the final sample size was 29 cases in PE group and 34 cases in OPEN group.64 patients met the inclusion criteria.In PE group,27 patients were followed up for 8.0(6.7,11.6)months,ranging from 3.9 to 20.9 months;In the OPEN group,34 cases were followed up and 3 cases were lost.The lost follow-up rate was 8.1%(3/37).The follow-up time was 20.6(11.6,32.1)months,ranging from 3.2 to 35.9 months.The demographic data,lesion segment,degree of spondylolisthesis,spinal stenosis classification,imaging classification,preoperative BV,HCT,CRP,CK and other baseline data of the two groups were comparable(P>0.05).The CRP in PE group was lower than OPEN group(t_1d=2.395,P=0.020;t_3d =2.640,P=0.011;t_5d= 2.646,P=0.011),CK level in PE group was lower than that in OPEN group(t_3d= 2.409,P=0.019).There were no blood transfusion cases in PE Group,and the transfusion rate was 8.8% in OPEN group.The blood loss in PE group was lower than that in OPEN group(t=3.919,P<0.001),the recessive blood loss was higher than that in OPEN group(t=7.318,P<0.001),the weight of recessive blood loss in PE group was(72.0 ± 10.2)%,and that in OPEN group was(32.9 ± 13.3)%.The improvement of the IDH,VLA and Cobb angle in both groups was statistically significant(P<0.05),and the postoperative IDH value of OPEN group was higher than that of PE group(t=2.082,P=0.042).The length of operation and the number of fluoroscopy in PE group were higher than that in OPEN group(P<0.05),and the height of fusion device in PE group was lower than that of OPEN group(U=647.500,P=0.002).The VAS,JOA and ODI of the two groups were significantly lower than those in the OPEN group(P<0.05),the VAS score of back pain in PE group was lower than that in OPEN group(t=2.441,P=0.018),JOA score in PE group was higher than that in OPEN group(t=2.093,P=0.041)10 days after operation;ODI in PE group was lower than that in OPEN group(t_1m= 2.314,P=0.024;t_3m=2.229,P=0.030).The excellent rate of PE group was 79.3% in Mac Nab group and 76.5% in OPEN group(?2=0.073,P=0.787).The complication rate of PE group was 11.1%(3/27),and that in OPEN group was 11.8%(4/34).Conclusion: CRP and CK have high sensitivity to soft tissue injury,and the response of tissue injury is mainly 5 days before and after operation.Compared with open TLIF,PE-LIF can reduce bleeding and blood transfusion rate.Recessive blood loss is the main way of PE-LIF.PE-LIF and open TLIF can effectively recover the height of collapsed vertebral space,improve the angle of VLA and Cobb,which is conducive to the physiological recovery and improvement of lumbar function.Compared with the open TLIF,PE-LIF has the advantages of less trauma,less postoperative low back pain and shorter hospital stay and so on.It is beneficial to the implementation of ERAS,shorten the hospitalization time of patients,and have the benefit of health economics and sociology.But in PE group,the operation time was longer and the fluoroscopy exposure was higher.There was no significant difference in the medium and long-term operation effect between the two methods.