Anatomic Measurement Of Cortical Bone Trajectory Screws For Lumbar Using Computed Tomography

Objective: To investigate the parameters of Lumbar cortical bone trajectory(CBT)Screws,and to guide clinical application.Methods: Analysis was made based on the computed tomography(CT)results of lumbars in normal adults.To measure the diameter,length,lateral angle and cephalad angle of the CBT screws,then to compare the differences of these datas in different segments and gender.Results: A total of 36 results were included,among which,there were 18 males and 18 females.There was no significant difference of the cephalad angle and lateral angle from segment L1 to L5.The diameter from segment L1 to L5 were(6.6±1.5)mm,(7.6±2.0)mm,(7.6±0.8)mm,(8.6±1.3)mm,(8.6±1.8)mm,and the diameter in segment L1 was smaller than those in segment L4 and L5(P=0.020,p=0.031).The length from segment L1 to L5 were 28.2(26.0,30.8)mm?30.9(20.4,39.6)mm?32.8(22.2,39.3)mm?46.7(26.3,49.4)mm,50.0(30.0,52.6)mm,and the length of CBT in segment L1 was shorter than those in segment L2 to L5(P=0.008,P=0.027,P=0.008,P=0.012),.the length of CBT in segment L2 was shorter than those in segment L4 and L5(P=0.035,P=0.047).The screw diameter for male were bigger than those for female from segment L2 to L5(P=0.042,P=0.041,P=0.035,P=0.037).The screw length for male were longer than those for female in segment L2,L3 and L5(P=0.017,P=0.043,P=0.026).Conclusions: The diameter and length of CBT screw show a trend of increase from segment L1 to L5.