Digital measurement of anatomical parameters associated with vertebral units fixed by ribs and pedicle fixation of T4-T10

Abstract

Objective To perform digital 3D measurement of anatomic parameters associated with vertebral units fixed by ribs and pedicle fixation of T4-T10, providing evidence for clinical application. Methods Spiral CT scan of T4-T10 vertebrae was conducted in 15 normal adults without spinal disorder. The data were imported into computer to establish units and disc models of thoracic and rib vertebrae T4-T10 using Mimics 16.0 software and Ansys 11.0 finite element software. The following data were measured in the vertebral pedicle-rib unit fixation group (group A) by software: transverse diameter of vertebral pedicle-rib unit, length of the outside pedicle screw, inclination angle of pedicle screw, and maximum and minimum inclination angles of pedicle screw; the following data were also measured in the pedicle fixation group (group B) by software: pedicle transverse diameter, length of pedicle screw, inclination angle of pedicle screw, and maximum and minimum inclination angles of pedicle screw. The corresponding parameters were compared between groups A and B. Results In both groups, the transverse diameters and screw lengths gradually increased with the increase in the vertebral sequence while the inclination angle of pedicle screw, and maxi-mum and minimum inclination angles of pedicle screw decreased with the increase in the vertebral sequence. All the parameters in groups A were significantly larger than the corresponding ones in group B (P<0.05). Conclusions Of the spinal segment of T4-T10, the rib vertebral unit fixation can provide greater safe screw angles and screw diameters for clinical surgery. This is of vital significance for reducing the surgical complexity and improving screw prehension. Key words: Thoracic vertebrae; Computer, digital; Imaging, three-dimensional; Vertebral unit fixed by ribs