Comparison of CT values in traditional trajectory, traditional cortical bone trajectory, and modified cortical bone trajectory

Abstract

Abstract Background 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. Methods 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-dimentional (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 CT values of ROI for the three techniques were significantly different between the same gander in each age group (P CBT > TT, the MCBT screw track has greater bone-screw surface strength and longer screw tracks than CBT, which is easier to reach the anterior column of the vertebral body contributing to superior biomechanical properties.

Keywords

• Pedicle screw
• Cortical bone trajectory
• Modified cortical bone trajectory
• CT value
• Zone of interest