The Feasibility Study Of Percutaneous Pedicle Screw Implantation In The Low Thoracic Spine With Anterior And Posterior Fluoroscopy

ObjectiveTo explore feasibility of the implantation of percutaneous pedicle screw under anterior-posterior fluoroscopic imaging guidance.In order to decrease the radiation exposure in the low thoracic spine.Method100 adults low thoracic x-ray and CT cases were collected,exclude abnormal spine.There were 47 males and 53 females,with a mean age of46.2 years（range,19 to 63）.The measure index include T9^T12 pedicle of vertebral transverse diameter,sagittal puncture angle（SPA）on x-ray.As to CT images,measure T9 T12 transverse puncture angle（TPA）,pedicle width（PW）,length of screw path（LSP）and The distance between the tangent line of the lateral margin of the pedicle and the posterior border of the superior articular process and the intersection of the tangent line of the medial margin of the pedicle and the horizontal line of the posterior edge of the vertebral body（M）.From Oct 2015 to Jan 2017,55 cases of patients materials who accepted percutaneous pedicle screw fixation of lower thoracic spine.25 of them underwent percutaneous pedicle cannulation simply under anterior-posterior fluoroscopic imaging guidance（AP group）.While the other 30 patients underwent percutaneous pedicle cannulation and screws insertion by routine anteriorposterior and lateral fluoroscopic imaging guidance（AP+L group）.Compared and evaluated fluoroscopy times of pedicle screw implantation,preoperative fluoroscopy,fluoroscopy of the whole operation,operation time,bleeding volume and average length of stay to two groups patients’ operation.According to Zdichavsky criteria,evaluate the accuracy of pedicle screw insertion in both groups.Result1.The results of imaging measurement100 cases of low thoracic spine X-ray results show: sagittal puncture angle（SPA）:T9^T12:（4.51±0.72）^0.56±0.39,left and right camber has no statistical meaning（P>0.05）.The results of transverse diameter of thoracic pedicle of vertebral arch: Left transverse diameter of pedicle of vertebral arch : T9^T12:（4.51±0.72）^7.51±0.59;right transverse diameter of pedicle of vertebral arch : T9^T12:（4.72±0.78）^T12（7.50±0.66）,left and right transverse has no statistical meaning（P>0.05）.CT results are as follows: left camber : T9 ^T12:（9.47±1.08）^12.09±0.88;right camber :T9^T12（9.54±0.78）^12.01±0.88;left and right camber has no statistical meaning（P> 0.05）.CT M results: left M values : T9^T12（21.00±0.87）^24.99±0.99;right M values : T9^T12（20.91±0.91）^25.02±1.04,the left and right sides of vertebral M values has no statistical significance（P>0.05）.The results of CT low thoracic pedicle width : left（PW）: T9^T12（6.24±0.51）^8.13±0.42;right（PW）: T9^T12（6.22±0.46）^8.14±0.39,the PW values of the left and right sides has no statistical significance（P>0.05）.The results of CT low thoracic length of screw path:left（LSP）: T9^T12（44.67±1.16）^48.16±0.56;right:（LSP）: T9^T12（44.60±1.17）^48.20±0.48,left and right side has no statistical significance（P>0.05）.2.The Clinical outcomeThe number of fluoroscopy in the operation of low thoracic spine pedicle screw fixation of two groups: preoperative fluoroscopy:5.04±0.73（AP group）,4.30±0.88（AP+L group）;intraoperative fluoroscopy:8.00±1.83（AP group）,12.53±2.13（AP+L group）;total fluoroscopy:13.00±2.08（AP group）.16.67±2.09（AP+L group）.Intraoperative fluoroscopy and total fluoroscopy of AP group and AP+L group has statistical significance（P < 0.05）.Length of stay（9.04±2.65,d）（AP group）,（9.77±1.91,d）（AP+L group）;operation time（88.20±14.71,min）（AP group）,（101.17±21.53,min）（AP+L group）;blood volume（83.20±19.73,ml）（AP group）,（98.33 ± 19.62,ml）（AP+L group）.Blood volume and operation time of two groups has statistical significance（P<0.05）.Two groups of length of stay has no statistical significance（P>0.05）.According to Zdichavsky criteria,64 pedicle screws were safely inserted in AP group,excellent screws were 59;appeared one Zdichavsky3 a screw and one Zdichavsky 2a screw at T9,one 2a screw at T10,one 2a screw at T11 and one 2a screw at T12.78 pedicle screws were safely inserted in AP+L group,excellent screws were 72;appeared one Zdichavsky 3b screw and one 2b screw at T9,one 2b screw and one 2a screw at T10,one 2b screw at T11,one 2a screw at T12.Two groups of patients showed no motor,sensory and other neurological damage.The excellent rate of pedicle screw position of two groups has no statistical significance（P>0.05）.Conclusion1.Detailed preoperative measurement of the target vertebral body which can provide reference for the specifications and angle of pedicle screw implantation.2.Percutaneous pedicle crew implantation under anterior-posterior fluoroscopic imaging guidance is feasible and safe,which can reduce the fluoroscopy times.