Biomechanical Effects of Anterior Decompression and Fusion With Cervical Two-Segments Different Internal Fixation Systems: A Finite Element Study

Abstract

One of the traditional surgical approaches for treating cervical spondylosis is anterior cervical discectomy and fusion (ACDF). The conventional titanium plate fixation method and the Zero-P internal fixation method are now the two most used anterior internal fixing techniques. Although these two fixation procedures have been clinically validated in part, their systematic theoretical analysis is still insufficient, and there are several flaws in the application comparison of double-segments cervical spine. The finite element simulation approach is used in this work to perform surgical simulation and stress analysis on two internal fixation methods. Firstly, we established a finite element model of the C3-C7 segments of the lower cervical spine and completed the validity verification of the model. Secondly, a finite element model of the internal fixation surgical method between Zero-P and traditional titanium plates was established. Finally, the cervical spine mobility and the stress of the internal fixation system under different postoperative movements were calculated. The results demonstrate that following typical titanium plate surgery, there is stress concentration in the intervertebral disc endplate, but the simulation results after Zero-P surgery are rather stable. The theoretical life of Zero-P fastening screws is rather limited, and typical titanium plates are prone to fatigue failure around the nail holes. The breadth of the Zero-P cage and the fusion site modification during surgery have a direct influence on the contact between the cervical spine and the instrument following surgery, which is also a major cause of edge fatigue failure.