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 torsion 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 torque 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 cervical 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.
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.
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.
ABSTRACT
Objective To study biomechanical properties such as range of motion (ROM), intervertebral disc stress, ligament tension of inferior cervical spinal segment after the treatment of Discover, Prodisc-C artificial intervertebral disc replacement, and anterior cervical discectomy and fusion (ACDF), as well as mechanical property changes of the prosthesis after implantation. Methods Three kinds of operation plan on C5-6 cervical disc degeneration were established: Discover model, Prodisc-C model and ACDF model, as well as C4-7 segment original model of cervical vertebra. Biomechanical property changes after operation in cervical spine C4-7 segment in sagittal, coronal and transverse section were analyzed. Results ROM changes of cervical segment C5-C6 were as following: in Discover model it increased by 12.7%-73.1%, Prodisc-C model increased by 74%-98%, ACDF decreased by 55.8%-71.8%. The stress of C4-5 intervertebral disc after Discover artificial disc replacement showed no obvious increase, while the stress of C6-7 intervertebral disc decreased by 33.2%-54.2% under flexion, extension and axial rotation conditions. The amplification of ligament tension in Discover model decreased by 30%-40% as compared to that in Prodisc-C model. The maximum stress of Discover model (36.72 MPa) appeared under flexion condition, which was smaller than that in Prodisc-C model. Conclusions Artificial disc replacement can help to keep movement performance for segment after surgery. As a newly developed artificial intervertebral disc prosthesis, Discover makes some progress in the aspect of decreasing ligament stress and maintaining spinal stability. The research findings will provide theoretical basis for the clinical study on ACDF and artificial cervical intervertebral disc replacement surgeries.