Measurement of anatomical parameters of anterior transpedicular root screw intervertebral fusion system of cervical spine

Abstract

Objective This study aims to investigate the feasibility of the anterior transpedicular root screw (ATPRS) intervertebral fusion system for the cervical spine and provide a basis for the design of the ATPRS intervertebral fusion system. Methods A total of 60 healthy adult cervical spine CT images examined from our hospital were selected, including 30 males and 30 females, with an average age of 39.6 ± 4.8 years. The image data was imported into Mimics 21.0 software in DICOM format for 3D model reconstruction. Simulated screw insertion was performed on both sides of the midline of the intervertebral space. The entry point (P1) was determined when the upper and lower screw paths did not overlap. When the screw was tangent to the medial edge of the Luschka joint, the insertion point was determined as the entry point (P2). Measurements were taken and recorded for the following parameters: distance from the screw entry point to the midline of the intervertebral space (DPM), the simulated screw length, inclination angle, cranial/caudal tilted angle, the anterior–posterior (AP) and mediolateral (ML) diameters of the cervical intervertebral space, the heights of the anterior, middle, and posterior edges of the cervical intervertebral space, and the curvature diameter of the lower end plate of the cervical vertebral body. Statistical analysis was performed on the measurement results. Results The screw entry area (P1P2) showed an increasing trend from C3-C7 in both male (2.92–6.08 mm) and female (2.32–5.12 mm) groups. There were statistical differences between men and women at the same level (P < 0.05). The average screw length of men and women was greater than 20 mm, and the upper and lower screw lengths showed an increasing trend from C3 to C7. In the area where screws could be inserted, the range of screw inclination was as follows: male group upper screw (47.73–66.76°), lower screw (48.05–65.35°); female group upper screw (49.15–65.66°) and lower screw (49.42–63.29°); The range of cranial/caudal tilted angle of the screw was as follows: male group upper screw (32.06–39.56°), lower screw (29.12–36.95°); female group upper screw (30.97–38.92°) and lower screw (27.29–37.20°). The anterior–posterior diameter and mediolateral diameter of the cervical intervertebral space showed an increasing trend from C3 to C7 in both male and female groups. The middle height (MH) of the cervical intervertebral space was greater than the anterior edge height (AH) and posterior edge height (PD), with statistical differences (P < 0.05). Conclusions Through the study of CT images of the cervical spine, it was determined that the ATPRS intervertebral fusion system has a feasible area for screw insertion in the cervical intervertebral space.

Biomechanical study of anterior transpedicular root screw intervertebral fusion system of lower cervical spine: a finite element analysis

“…So, the ATPRS technology, in theory, mitigates the risks associated with screw insertion. In our previous study, we have indicated the feasibility of the ATPRS intervertebral fusion system in the cervical spine ( Ye et al, 2023 ). The system comprises three primary components: the insert positioned between the upper and lower vertebral bodies, the first screw connecting the upper vertebral body and the insert, and the second screw connecting the lower vertebral body and the insert.…”

“…The system comprises three primary components: the insert positioned between the upper and lower vertebral bodies, the first screw connecting the upper vertebral body and the insert, and the second screw connecting the lower vertebral body and the insert. Besides, based on our previous radiographic study of the ATPRS fixed system, the screw hole positions in the cage were determined ( Ye et al, 2023 ). However, there is a lack of direct biomechanical study.…”

“…However, there is a lack of direct biomechanical study. Therefore, the primary objective of this study is to conduct FEA to scrutinize and compare the alterations in range of motion (ROM) and stress distribution within the ACLP, the self-designed ATPS fixation system (ZL:201120445914), and the self-designed ATPRS intervertebral fusion system (ZL:2019202500823) in the context of a two-level discectomy decompression and bone graft fusion surgery ( Zhao et al, 2018 ; Ye et al, 2023 ). This analysis can serve as a foundational basis for the subsequent design and application of the ATPRS intervertebral fusion system.…”