ABSTRACT
Objective To investigate the influence of ROI-C cervical implantation in the C5-6 segment on the C3-7 range-of-motion (ROM), biomechanical properties of the intervertebral disc and the vertebral body, and the mode of force transmission. Methods Two types of surgeries, ROI-C implantation and autograft fusion with plate fixation, were considered to establish the finite element model of cervical C5-6 segment degeneration. The ROM of C3-7 during flexion, extension, lateral bending, and axial rotation, as well as stress distributions on the adjacent discs, vertebral body, and implanted devices under two procedures, were analyzed. Results ROI-C implantation had a relatively small influence on the ROM of the adjacent segment. The stress on the vertebral discs was reduced, but the stress on the vertebral body increased significantly, with the C5 vertebral body stress increasing by 251%. In the fusion surgery model, the ROM of the surgical segment was reduced by 86%-91%, while the ROM of the adjacent segments and the stress on the vertebral disc and vertebral body increased significantly. Conclusions ROI-C implantation surgery has a relatively small influence on the cervical ROM and the intervertebral disc, and it has a greater impact on the vertebral body. The research findings provide a theoretical basis for the design of operation plans and clinical studies on ROI-C implantation and autograft fusion with plate fixation.
ABSTRACT
Objective To establish the three-dimensional finite element model of human lower cervical spine C3-7 motion segments after anterior cervical corpectomy and fusion (ACCF) surgery with titanium mesh and bone graft,and to analyze the stability of cervical spine and stress distribution of internal fixation devices after ACCF surgery.Methods The finite element model of cervical spine C3-7 segments after ACCF of C5 segment with titanium mesh,bone graft,plate and screw fixation was established,and C3-7 segment intact model of cervical vertebra was also constructed.The torque moment of 0.5,1.0,1.5,2.0 N · m was applied to the ACCF surgery model.The ROM,maximum stress in facet joint and stress distributions on internal fixation devices under flexion,extension,lateral bending and axial rotation movement were analyzed.Results ROM of reconstructed C5 segment increased with the torque moment increasing after ACCF surgery.In the case of 1.0 N · m tomue moment and 50 N preload,the ROM of reconstructed C5,C3-4,C6-7 and C3-7 segment was reduced by 81％,62％,58％ and 80％ compared with the intact model.The maximum stress in facet joint of reconstructed C5 segment reduced and the stress in adjacent segments significantly increased.The stress of titanium mesh was mainly distributed on the compression side of movement,and high stress was located in the roots of screws.Conclusions ACCF surgery can promote the stability of cewical spine,decrease the stress in facet joint of operation segment,and has better treatment effect on easing compression from spinal cord caused by cervical spondylotic myelopathy.The research results will provide some theoretical basis for clinical application of ACCF surgery.