| Recent decades,satisfactory results have been achieved for lumbar fracture and lumbar spondylisthesis with posterior pedicle internal fixation instrument. However,the reported complications of the instrumentation should be appealled to our emphases,which associated with operative procedure.The essential procedure is to ensure the pedicle screw plating in the pedicle of vertebrae accurately.As a result,we make some reseach in the anatomic feature of lumbar vertebrae arch in order to find some way increasing the success rate of plating pedicle screw.1. The anatomic study in the pedicle of vertebrae archUsing 30 adults dry lumbar specimens,measure the date of PW(pedicle width),PA(pedicle angle),SSA(sagittal screw angle),the quantitative relationship between the lateral margin of the superior facet and the pedicle center of lumbar vertebrae,the quantitative relationship between the center of the pedicle and axis of the transverse process.Result:PW:L1: 7.2 ± 1.8mm, L2: 8.6 ± 1.4mm, L3: 10.4± 1.9mm, L4: 11.7 ± 2.1mm, L5: 15.2 ± 2.8mm,and the minimum PW of L1: 3.9mm,the maximum PW of L5: 16.6mm. PA: L1: 7.2 ±1.1° , L2: 8.7 ±2.3° , L3: 13.2 ±1.6° , L4: 17.1 ±2.8° , L5: 23.4 ±3.1° . SSA: L1:100.38±4.76° , L2:106.13 ± 6.34° , L3:109.22±7.39° , L4:114.15 ± 8.46° , L5:120.06±6.23° .As a common rule, mostly the center of lumbar vertebrae is inside the margin of the superior facet in L1-L3,and the center of lumbar vertebrae is just in the place of the margin of the superior facet in L4 frequently,the center of lumbar vertebrae is lateral to the margin of the superior facet mostly; the axis of the transverse process is inferior to the center of pedicle in L1-L3 as well,more than an half of the axis of the transverse process is in the place of the center of pedicle in L4, many of axis of the transverse process is superior to the center of pedicle in L5.Measure the direction of spinous process and the angle of spinous process,we find the most of direction of spinous process is to right,the range of angle is from 0° to 11 ° .So we believe the way to plate the pedicle screw by anatomic feature is not ideal.2. Estimate the method to plate the pedicle screw on the bass of the digital data of the transverse screw angle, sagittal screw angle, the distance between two point where the screw is plated into the pedicle of vertebrae archMeasure the digital data of PW and TSA by CT;compare it with the data which is measured by instrument.Measure the distance between two point where the screw is plated into the pedicle of vertebrae arch.Plate the screw based on the data of the transverse screw angle and the distance between two point where the screw is plated into the pedicle of vertebrae arch.Estimate the result by pop-rate X picture, measure the entering nail screw length,the rate of sagittal length of nail to the lumbar vertebrae.Result:There is no significant diference between the data of PW , ISA measured by CT and the one mesured by instrument,so we thought it s accurate way to measure PW and TSA by CT.The data ofTSA followed the rule:that L1: 5° , 1.2: 10° , L3:15° , L4: 20° , L5: 25° ,which is rendered by AO.We measure the distance between two points where the screw is plated into the pedicle of vertebrae arch.Plate the screw in the help of instrument which is invited following measured data. By pop-rate X picture we found the length of screw is safe in 45mm-55mm,the length of screw in L1 to L3 is increasing with the number of lumbar,however the length of it in L4 to L5 is decreasing.The rate of sagittal screw length to the sagittal length of lumbar is L1: 83.1 ±4.2 (78-88) %, L2: 84.4 ± 3.7 (78-89) %; L3: 88.0±4.4 (83-92) %; L4: 90.1±3.4 (84-94) %; L5: 93.4±1.8 (90-96) %. .3 interior side of the pedicle of vertebrae arch are broken by screw. And the avarage rate of distance bewteen screw and the interior side of pedicle of vertebrae arch to PW is 0.37.It s worked out the screw is nearly plated in the center of pendicle of vertebrae arch. ResultThe way to plate the pedicle... |
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