Biomechanical analysis of a newly designed and 3D printed plate-locking interbody cage: an observational study of finite element analysis.

Anterior cervical interbody fusion (ACDF) has become a classic surgical procedure for the treatment of cervical degenerative diseases, and various interbody cages are widely used in this procedure. We used 3D printing technology to produce a new type of plate-locking cage, anticipating to achieve high fusion rate with the high biomechanical stability. This study is to compare the biomechanical characteristics between a newly designed interbody cage and a conventional Zero-profile cage during ACDF using finite element analysis. The CT images of a 35-year-old healthy male were extracted and saved in DICOM format. Mimics Research 19.0, Geomagic Wrap 2017, NX12. 0, Abaqus 6.14 were used to construct the finite element models, then, titanium plate, titanium screw, cages, and the residual parts of both groups were assembled with reference to the surgical approach of ACDF (C4/5), following the successful establishment of both surgical models, a total of six boundary and loading conditions were tested, including flexion, extension, left and right bending, and left and right axial torsion. It is found that the plate stress peak of the new cage group decreased 73.78 MPa, 70.00%; 77.17 MPa, 70.67%; 59.77 MPa, 64.97%; 49.94 MPa, 58.28%; 44.55 MPa, 68.38%; 46.14 MPa, 68.00% in flexion, extension, left bending, right bending, left axial torsion and right axial torsion, respectively. There were no obvious increases of C5 upper endoplate stress peak between these two surgical models (< 50%), except 11.68 MPa, 153.08%; 6.55 MPa, 51.45%; in flexion and extension. The 3D-printed porous plate-locking cage was shown to be biomechanically stable compared to the conventional Zero-profile cage, and it is worth noticing that the stress on the plate of the new cage is less than that on screw of the conventional cage, which indicates that the risk of fracture, loosening, and prolapse of the new cage is less likely to occur.