Individual Threshold And Clinical Application Of A Pedicle Piercer For Prewarning

Objective The purpose of this study is to explore the corresponding relation between the warning threshold and the CT value of vertebral body, thereby realizing individualized threshold value. Apply this warning device during pedicle screw site preparation to test the warning effect.Methods From June,2009 to October,2010,80 cases single-segment pedicle fixation patients were selected in the Department of Orthopaedics, the NO.175 Hospital of PLA. All patients were examined preoperatively by radiography and CT scaning.80 cases were randomly divided into control and experimental groups, each with 40 patients. Two groups in age, sex ratio, the type of cases and JOA scores were no significant difference. A total of 320 pedicle screws were placed in each 160. The control group:the road of pedicle screw was ready with using an ordinary piercer. The experimental group:the road of pedicle screw was ready with using warning piercer, according to CT values measured before surgery to set the alarm warning threshold. The average time (seconds), intraoperative use of C-arm fluoroscopy (times), and blood loss (ml) were recorded respectively. After surgery, all patients received routinely radiography and computer tomographic scan. All the pedicle screws were determined with fPAX image editing system. Screws placed exactly were classified according to the pedicle screws is worn, wear clothing and worn out from the direction. The excellent rate, the time of planting nails, and bleeding were compared between the two groups. The lineal regressive equation was concluded through the analysis on the two relative regression varieties between the vertebral body CT value and the warning alarm threshold. The precision, the time of planting nails, bleeding, the average fluoroscopy and JOA scores were analysed respectively between two groups.Results With the linear regression analysis, the CT value of the pedicle and warning threshold had significant linear relationship. Linear regression equation:y^=6.549+0.021x. Correlation coefficient R=0.992, regression coefficient of the test statistic t=28.949, accompanied by probability values P=0.000.With the Rank sum test, the results show that the precision was significantly higher in the experimental group (P<0.05). With the PearsonΧ2 test, the results show that the fine was significantly higher in the experimental group (P< 0.05). the average time per screw of the experimental group reduced by 16.8% compared with the control group; the average number of Fluoro Shots perspective reduction of 39.7% compared to the control group; blood loss decreased 20.1% compared with the control group. There was a significant difference between two groups about postoperative JOA score (P< 0.05).Conclusions Pedicle Warning Piercer can provide audio and luminary alarm in the pedicle screw fixation. The CT value of the pedicle and warning threshold had significant linear regression. By reference to the value of preoperative CT can set individual alarm threshold, It can improve the precision and decrease the operation time, frequency of fluoroscopy and bleeding. It can be used as an auxiliary equipment on the traditional pedicle screw fixation.