Anterior cervical transpedicular screw fixation system in subaxial cervical spine: A finite element comparative study

Abstract

Multilevel cervical corpectomy has raised the concern among surgeons that reconstruction with the anterior cervical screw plate system (ACSPS) alone may fail eventually. As an alternative, the anterior cervical transpedicular screw (ACTPS) has been adopted in clinical practice. We used the finite element analysis to investigate whether ACTPS is a more reasonable choice, in comparison with ACSPS, after a 2-level corpectomy in the subaxial cervical spine. These 2 types of implantation models with the applied 75 N axial pressure and 1 N • m pure moment of the couple were evaluated. Compared with the intact model, the range of motion (ROM) at the operative segments (C4–C7) decreased by 97.5% in flexion-extension, 91.3% in axial rotation, and 99.3% in lateral bending in the ACTPS model, whereas it decreased by 95.1%, 73.4%, 96.9% in the ACSPS model respectively. The ROM at the adjacent segment (C3/4) in the ACTPS model decreased in all motions, while that of the ACSPS model increased in axial rotation and flexion-extension compared with the intact model. Compared to the ACSPS model, whose stress concentrated on the interface between the screws and the titanium plate, the stress of the ACTPS model was well-distributed. There was also a significant difference between the maximum stress value of the 2 models. ACTPS and ACSPS are biomechanically favorable. The stability in reducing ROM of ACTPS may be better and the risk of failure for internal fixator is relatively low compared with ACSPS fixation except for under lateral bending in reconstruction the stability of the subaxial cervical spine after 2-level corpectomy.

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

“…However, the maximum stress at the bone-screw interface in the ATPS model was lower than that in the ACLP model during flexion and extension. The stress cloud map indicated that the maximum stress on the screws and plates mainly occurs at the contact area between the screws and plates, consistent with previous studies ( Li et al, 2022 ) ( Figure 6 ). In Table 3 , the maximum stress on the plate in the ATPS model was greater than that in the ACLP model during flexion, extension, and lateral bending, but lower during axial rotation.…”

“…Previous investigations have revealed that the pull-out strength of ATPS surpasses that of cervical vertebral body screws (VBS) by 2.5 times, and it can yield comparable outcomes to the combined anterior and posterior surgeries ( Koller et al, 2008b ; Koller et al, 2009 ; Koller et al, 2010 ; Koller et al, 2015 ). Nevertheless, our research team, through a comprehensive series of studies on ATPS, has identified some ATPS limitations, including a heightened risk of screw insertion and technical complexity ( Zhao et al, 2014 ; Zhao et al, 2016 ; Zhao et al, 2018 ; Li et al, 2022 ). Those all curtailed its widespread clinical applicability.…”