Abstract:

Objective　To investigate the three-dimensional relationship between the spinous processes of lumbar vertebrae and the pedicle insertion channel, and to provide anatomical basis for lumbar spine fixation and the application of auxiliary fixation techniques.　Methods　CT scan images were imported into Mimics 18.0 software (Materalise) and UG13.2 imaging software for measurement. Firstly, the line L was located in the pedicle insertion channel, and the line M represented the medial axis of the spinous processes of lumbar vertebrae, then the angles between two lines and the three-dimensional reference plane in 70% and 90% boundary depth were measured, respectively. Secondly, the line L and the anterior surface of centrum intersected at A, the line L and the posterior surface vertebral arch intersected at B,the line L intersected the coronal plane at C were observed. Thirdly, the line M intersected the anterior wall of pedicle plate and the back edge of spinous process at D, E respectively were observed. Finally, the distances between point A, B, C and line L, M and three-dimensional reference plane were measured respectively. 　Results　(1)The angels between the medial axis of the lumbar spinous process and the sagittal, coronal and horizontal planes were 2º~3º, 11º ~18º and 71º ~77º respectively. The angles between the pedicle insertion channel and the sagittal plane in 70%, 90% boundary depth were 7º~22º and 16º~33º respectively. The angles between the pedicle insertion channel and the horizontal plane in 70%,90% boundary depth were 1.8º~2.9º and 1.4º~2.4º. The angles between the pedicle insertion channel and the coronal plane in 70%, 90% boundary depth were 67º~82º and 56º~73º; (2)With the decrease of the level of lumbar vertebrae, the distance between points and lines changed regularly; (3) The distance between points and planes changed regularly.　Conclusion　The three-dimensional relationship between the medial axis of spinous processes and the pedicle insertion channel in 70%, 90% boundary depth in this study have been analyzed, and the anatomical basis been laid for percutaneous cervical pedicle screw placement and its instrument design.

Key words: Medial axis line of spinous process, Pedicle insertion channel, Three-dimensional relationship, Lumbar vertebra