Comparative Study On The Clinical Effects And Imaging Evaluation Of Three Different Surgical Procedures Of Single-level Lumbar Fusion:Robot-assisted MISTLIF,TLIF And MIDLIF

Lumbar fusion is still a widely accepted method for the management of various lumbar diseases.Although many studies reported that the early results of lumbar fusion are promising,the long-term clinical effects were compromised because of chronic postoperative back pain and adjacent segment disease(ASD).The reasons include patient factors,such as overweight,osteoporosis and overload,as well as iatrogenic injury factors.The conventional posterior lumbar fusion instrumented with pedicle screw requires to reveal the bone structures such as lamina and facet joint,prone to violate the superior facet joint violation.The extensive detachment of paravertebral muscles and prolonged wide retraction can result in paravertebral muscle injury.Cranial facet joint violation and paravertebral muscle injury after conventional open approach are considered risk factors of chronic back pain and adjacent segment degeneration.How to reduce the rate of FJV and paravertebral muscle injury,improve clinical effects have become an increasing concern for many surgeons.Robot-assisted screw placement and cortical bone trajectory screw are new techniques emerging in recent years.Many studies have reported that these two insertion techniques can reduce the degree of paravertebral muscles injury and the rate of superior FJV.However,no study has compared the protective effects of these two techniques on the facet joint and paravertebral muscle.Considering the special anatomical proximity of the pedicle,screw malposition can cause serious complications.Hence,screw accuracy has always been one of the criteria for the measurement of the quality of each screw implantation technique.Both RA screw implantation and CBT screw techniques are emerging minimally invasive techniques that can reduce paravertebral muscle dissection,but findings on the accuracy of both techniques are inconsistent.Therefore,this study simultaneously analyzed the accuracy of screws,incidence of superior FJV,change of paravertebral muscles and clinical efficacy of both implantation techniques,and compared them with conventional PS technology in order to provide a reference for clinical application.OBJECTIVEStudy 1: To compare the rates of superior facet joint violation(FJV)among robotassisted pedicle screw(RA),traditional pedicle screw(PS),and cortical bone trajectory screw(CBT)techniques.The possible risk factors of FJV were also analyzed.Study 2: To compare the intra-pedicular accuracy among robot-assisted pedicle screw(RA),traditional pedicle screw(PS),and cortical bone trajectory screw(CBT)techniques.Study 3: To compare the clinical effects and paravertebral muscle changes of three different implantation techniques in single lumbar 4-5 fusionMETHODSStudy 1: A total of 166 patients with lumbar degenerative diseases requiring posterior L4-5 fusion were retrospectively included and divided into RA,PS,and CBT groups from March 2019 to December 2021.The grade of FJV were evaluated.Multivariate logistic regression analysis was conducted to assess the factors associated with proximal FJV.Study 2: A total of 182 patients with lumbar degenerative diseases requiring single level posterior fusion were retrospectively included and divided into RA,PS,and CBT groups from March 2019 to December 2021.The perioperative indices were compared among the three group.The intra-pedicle accuracy was evaluated.The possible risk factors of intra-pedicle accuracy were also analyzed.Study 3: We studied 90 patients with lumbar degenerative diseases requiring posterior L4-5 fusion and divided them into RA,PS,and CBT groups from March 2019 to February 2021.More than 1 year postoperatively,all the patients were followed up with the visual analogue scale(VAS)and Oswestry disability index(ODI),and 31 patients were evaluated using MRI.This enabled the cross-sectional area(CSA)and musclefat-index(MFI)of paravertebral muscles to be compared at the adjacent levels.RESULTSStudy 1: Cephalad FJV occurred in 28.2% of screws in RA,45% in PS,and 21.6% in CBT.A significantly higher rate of FJV was observed in PS compared with RA and CBT.Multiple logistic regression analysis revealed that age,implantation technique and facet angle were independently associated with superior FJV.Study 2: The RA group had the lowest intra-operative blood loss,post-operative drainage,and post-operative hospital stay but had the longest surgical time.In the RA,87.3% of the screws were perfectly positioned(grade A),98.3% of the screws were clinically acceptable screws(grade A+B);the rate of optimal and clinically acceptable screw in the PS were 82.2%,97.7% respectively;in the CBT,78.1% screws were grade A,94.3% screws were grade A+B.The rate of optimal screw was significantly greater in the RA group than in the CBT group(p=0.009).Univariate analysis showed that the implantation technique was associated with the screw accuracy.Study 3: The RA group had least postoperative back pain and lowest postoperative ODI scores at 6 months and last follow-up.The adjacent paravertebral muscles atrophy to different degrees,and atrophy of distal paravertebral muscles was heavier than proximal,and multifidus was more obvious than erector spinae.The degree of multifidus atrophy and increase in MFI were similarly less marked in RA compared with the open groups at the distal level.No significant difference was found in the CBT and PS groups.Multiple analysis showed that the change rate of f CSA of distal multifidus is an independent risk factor for the improvement rate of ODI score(p=0.005).CONCLUSIONSStudy 1: RA and CBT were associated with fewer proximal FJV.Age,implantation technique and facet angle were independent risk factors of superior FJV.Study 2: The perioperative indices of RA were better than open approach but longer operation time.A better intra-pedicular accuracy was found in RA than in CBT.Freehand CBT technique can achieve high screw accuracy(94.3%),but still lower than RA and PS.Study 3: The RA group had least postoperative back pain and lowest postoperative ODI scores at 6 months and last follow-up.The change of distal multifidus in the RA group is less than the open groups.The postoperative clinical effects and multifidus atrophy were comparable in the CBT and PS groups.The change rate of multifidus f CSA is an independent risk factor for the improvement rate of ODI score.