| Objective: To compare the CT values and length of the screw tracks of traditional trajectory(TT),cortical bone trajectory(CBT),and modified cortical bone trajectory(MCBT)screws and investigate the effects on the biomechanics of lumbar fixation,providing a theoretical basis for the clinical application of MCBT.Methods: CT data of lumbar spine(including L4 and L5)were collected from the imaging department of our hospital from January 2015 to January 2022.CT scan data of 60 L4 and L5 lumbar spine were retrieved and divided into 4 groups(10 male and 10 female cases in the 20-30 years old group and 20 male and 20 female cases in the 30-40 years old group).3-dimen-tional(3D)model were established using Mimics 19.0 for each group and the placement of three techniques was simulated on the L4 and L5,and the part of the bone occupied by the screw track was set as the region of interest(ROI).The mean CT value and the actual length of the screw track were measured by Mimics 19.0.Results: the mean CT values of the ROI around the screw tracks of the L4 and L5 vertebrae by age and gender for TT,CBT and MCBT screw: 21-30 years group,in L4 male were 258.8±53.95 HU,447.3±108.4 HU and511.0±92.9 HU,in L4 female were339.3±68.3 HU,535.4±109.3 HU and 612.7±100.8 HU;in L5 male were 235.2±64.2 HU,430.5±96.7 HU and 493.1±116.1 HU;in L5 female were298.3±67.7 HU,505.4±104.8 HU和591.7±122.9 HU;31-40 years group,in L4 male were228.8±48.3 HU,438.8±112.6 HU and 501.9±113.6 HU,in L4 female were 278.4±74.9HU,492.1±129.9 HU and 576.7±133.1 HU;in L5 male were 204.4±42.1 HU,422.0±104.1HU and 465.6±101.7 HU,in L5 female were 257.9±61.4 HU,496.1±112.2 HU and569.7±107.7 HU.The mean CT values of the ROI around the screw tracks of different techniques for men and women in each age group:21-30 years group,in male were247.0±59.0 HU,438.9±100.4 HU and 502.1±102.7 HU,in female were 318.8±69.4HU,520.4±105.4 HU and 602.2±109.8 HU;31-40 years group,in male were 216.6±46.4HU,430.4±107.4 HU and 483.7±108.0 HU,in female were 268.1±68.4 HU,494.1±119.8HU and 573.2±119.6 HU.the mean length of CBT and MCBT trajectory were 34.6±0.69 mm and 39.1±1.02 mm.The CT values of ROI for the three techniques were significantly different between the same gander in each age group(P < 0.05).The difference of screw track lengths for CBT and MCBT in the male and female is significant(P < 0.05).Conclusion: According to the comparison of the CT values of the three nail tracts,the results were: MCBT > CBT > TT,in addition,the nail tract of MCBT was longer than that of CBT. |
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