Objective: To compare the biomechanical properties of a new memory compression alloy plate and traditional titanium plate after anterior cervical discectomy and fusion (ACDF).
Methods: A finite element model of the C3-7 segments was developed and validated. The C5-6 disc was removed, and an intervertebral cage made of peek material was implanted. Then, a new memory compression alloy plate composed of Ti-Ni memory alloy and a traditional titanium plate were integrated at the C5-6 segment. All models were subjected to a load of 73.6 N to simulate the head weight and 1 Nm of flexion-extension, lateral bending, and axial rotation. The range of segmental motion (ROM) and stress on the prostheses, adjacent discs, and endplates were analyzed.
Results: Compared with intact status, ACDF with the new prothesis and traditional titanium plate reduced the ROM of C5-6 in six directions by 95.2%-100% and increased that of adjacent discs (C4-5 and C6-7) by 4.8%-112.5%. Adjacent disc stress peaks were higher for the traditional titanium plate (0.7-4.2 MPa) than for the new prosthesis (0.6-4.1 MPa). Endplate stress peaks were the highest in ACDF with the new prosthesis (15.6-53.3 MPa), followed by ACDF with traditional titanium plate (5.0-29.4 MPa). Stress peaks were significantly lower for the new prothesis (12.8-52.3 MPa) than for the traditional titanium plate (397.0-666.1 MPa).
Conclusions: The new prosthesis improved the immediate stability of the surgical site and had an elastic modulus that was smaller than that of traditional titanium plate, making it conducive to reducing stress shielding and the impact on the adjacent intervertebral disc.
Copyright © 2020 Jiantao Liu et al.