Objective The application of intraoperative evoked EMG monitoring during lumbar pedicle screw fixation and to find new stimulus threshold criterion.Methods The validity of the evoked EMG monitoring in detecting the malposition of the pedicle screws was tested again by animal experiment.Nineteen patients was inserted pedicle screws with persistent evoked EMG monitoring via tap stimulator,and the electric current was set at 30% of bone threshold of the same pedicle,all patients were ohecked by CT scan to prove the outcome.Results Thirty-two pedicles of six dogs were inserted Kirchner wires.The stimulate thresholds of mal-position wires had significant difference with those of normal-position wires.During clinical trial,122 screws were inserted in to nineteen patients.Four screws were positive during intraoperative evoked EMG monitoring.Of which one screw was confirmed as mal-position during operation and was then adjusted;another screw was found to be mal-positioned by CT scan post-operation;the other two screws were found normal by CT scan.The sensitivity of this technique was 100% and the specificity was 98%.Conclusion Intraoperative evoked EMG monitoring during lumbar pedicle screw fixation can detect the mal-positioned screws and to protect the nerve roots.The stimulate current may set at 30% of the bone threshold of the relevant pedicle.

Objective A meta-analysis is to be performed to compare the entire efficacy on decompression (D) alone and decompression with fusion (F) for patients with 1-2 level lumbar stenosis (LSS) regardless of degenerative spandylolisthesis (DS) based on published RCTs.Methods The databases include Pubmed,Embase,Cochrane Library and Web of Science from January 1970 to March 2018 with a certain search strategy and inclusion criteria.Two reviewers assessed eligible trials,evaluated articles quality and extracted information independently and the information included basic characteristics of demographic information,primary and secondary measures,then data synthesis and meta-analysis was progressed as well as subgroup analysis by DS and follow-up time (36 months).Continuous variables were reported as weighted mean difference (WMD) and dichotomous variables were reported as odds ratios (ORs).Finally the strength of evidence and grade of recommendation was evaluated by the grades of recommendation,assessment,development and evaluation (GRADE) system for the overall outcome.Results A total of 9 RCTs with a low to moderate risk of bias met inclusion criteria with a total of 857 patients (367 were in D group and 490 were in F group) in 1-2 level operation and the average age,sex ratio and preoperative visual analogue scale (VAS) were of no significance.In primary measures,there were no statistical difference in VAS changes on back and leg pain between D and F group [MD=-0.03,95％ CI (--0.38,0.76),Z=0.08,P=0.94;MD=0.1 1,95％CI (-1.08,1.30),Z=0.18,P=0.86,respectively];Patients' satisfaction was of no difference between the two groups (OR=0.74,P=0.48),together with the change of Oswestry disability index (ODI,P=0.29) and European quality of life-5 dimensions (EQ-SD,P=0.41).As to the secondary measures,there were no difference in the rate of complication (OR=0.75,P=0.50) and reoperation (OR=1.93,P=0.11) while a statistical significance of longer operation duration (P=0.000),more blood loss (P=0.004),longer hospital stays (P=0.000) but amazing lower rate of ASD (OR=2.35,P=0.02) in F group.The subgroup analysis on whether combined with DS showed that basically all of the compared measures were in consistency with the whole meta-analysis;As to the follow-up,there was a higher reoperation rate in middle-to-long term (＞ 36months) in D group while the other measures were in line with the overall meta-analysis and adjacent segment degeneration/disease (ASD) was the most seasons of reoperation yet no matter the follow-up time.According to the GRADE system,the grade of this meta-analysis is of "High" quality.Conclusion F group has no better clinical results than D alone in short-segment LSS,regardless of DS,and even further,no significant change with shot-term or middle-to-long term follow-up.F approach has a longer duration of operation,more hospital stays and more blood loss,even perhaps a lager cost.According to the GRADE,the grade of this meta-analysis is of "High" quality,the grade strength of recommendation was "Strong".