Posterior instrumentation is a common fixation method used in the treatment of spinal diseases.However,the role of different models of fixation system in improving fixation stability in these fractures has not been es...Posterior instrumentation is a common fixation method used in the treatment of spinal diseases.However,the role of different models of fixation system in improving fixation stability in these fractures has not been established.Comparative investigation between posterior rigid fixation(pedicle screw)and four models of posterior dynamic fixation(B Dyne,Elaspine,Bioflex,Coflex rivet)may elucidate the efficacy of each design.The purpose of this study was to investigate the biomechanical differences between rigid fixation and dynamic fixation implantation by using finite element analyses.The goal of the present study was to evaluate the efficacy of five fixation systems mounted on L4-L5 motion segment.In this numerical study,finite element model of an L4-L5 segment was developed from computed tomography image datasets.Five fixation devices were also implanted internally to the motion segment.Another model with an intact intervertebral disc was also analysed for comparison.Loads simulating the physiological flexion,extension and lateral bindings were applied to the superior surface of L4.Results showed that the Elaspine,Bioflex,Coflex rivet and pedicle screw fixation implantation could provide stability in all motions and reduce von Mises stress in the cortical and spongy bone at the surgical segment L4-L5.Moreover,maximal von Mises stress in the annulus disc was observed in dynamic systems but within the safe range.The greater movement of the motion segment was also appeared in dynamic fixations.Existence of the fixation systems reduced the stress on the intervertebral disc which might be exerted in intact cases.Use of the fixation devices could considerably reduce the load on the discs and prepare conditions for healing of the injured ones.Furthermore,dynamic modes of fixation conferred the possibility of movement to the motion segments in order to facilitate the spinal activities.The numerical results showed that the posterior fixation system(rigid and dynamic)played a very important role in the absorption and minimization of stresses.On the other hand,the tow systems(rigid fixation and dynamic fixation)played such a great role in reducing the stress compared to other synthetic discs.In general,the posterior fixation system gave a lower level of stress in the cortical bones and the spongy bones of the L4-L5 lumbar segment compared to the intact model.展开更多
Orthopedic fixation devices are widely used in treatment of spinal diseases. It is expected thatapplication of dynamic stabilization confers valuable movement possibility besides its main role ofload bearing. Comparat...Orthopedic fixation devices are widely used in treatment of spinal diseases. It is expected thatapplication of dynamic stabilization confers valuable movement possibility besides its main role ofload bearing. Comparative investigation between pedicle screw model rigid fixation and (B Dyne,Elaspine, Bioflex, Coflex rivet) models dynamic fixation systems may elucidate the efficacy of eachdesign. The goal of the present study is to evaluate the efficacy of five fixation systems mounted onL4-L5 motion segment. In this numerical study, a 3D precious model of L4, L5 and their intervertebraldisc has been employed based on CT images. Five fixation devices have been also implantedinternally to the motion segment. Finite element method was used to evaluate stress distribution inthe disc and determine the overall displacement of the segment as a measure of movement possibility.The results show that the Coflex rivet implantation can provide stability in all motions and reduce discannulus stress at the surgical segment L4-L5. On the other hand, maximum stress in the disc has beenobserved in dynamic systems but within the safe range. The greater movement of the motion segmenthas also appeared in dynamic fixations. Existence of the fixation systems reduced the stress on theintervertebral disc which might be exerted in intact cases. Use of the fixation devices can considerablyreduce the load on the discs and prepare conditions for healing of the injured ones. Furthermore,dynamic modes of fixation confer possibility of movement to the motion segments in order tofacilitate the spinal activities.展开更多
文摘Posterior instrumentation is a common fixation method used in the treatment of spinal diseases.However,the role of different models of fixation system in improving fixation stability in these fractures has not been established.Comparative investigation between posterior rigid fixation(pedicle screw)and four models of posterior dynamic fixation(B Dyne,Elaspine,Bioflex,Coflex rivet)may elucidate the efficacy of each design.The purpose of this study was to investigate the biomechanical differences between rigid fixation and dynamic fixation implantation by using finite element analyses.The goal of the present study was to evaluate the efficacy of five fixation systems mounted on L4-L5 motion segment.In this numerical study,finite element model of an L4-L5 segment was developed from computed tomography image datasets.Five fixation devices were also implanted internally to the motion segment.Another model with an intact intervertebral disc was also analysed for comparison.Loads simulating the physiological flexion,extension and lateral bindings were applied to the superior surface of L4.Results showed that the Elaspine,Bioflex,Coflex rivet and pedicle screw fixation implantation could provide stability in all motions and reduce von Mises stress in the cortical and spongy bone at the surgical segment L4-L5.Moreover,maximal von Mises stress in the annulus disc was observed in dynamic systems but within the safe range.The greater movement of the motion segment was also appeared in dynamic fixations.Existence of the fixation systems reduced the stress on the intervertebral disc which might be exerted in intact cases.Use of the fixation devices could considerably reduce the load on the discs and prepare conditions for healing of the injured ones.Furthermore,dynamic modes of fixation conferred the possibility of movement to the motion segments in order to facilitate the spinal activities.The numerical results showed that the posterior fixation system(rigid and dynamic)played a very important role in the absorption and minimization of stresses.On the other hand,the tow systems(rigid fixation and dynamic fixation)played such a great role in reducing the stress compared to other synthetic discs.In general,the posterior fixation system gave a lower level of stress in the cortical bones and the spongy bones of the L4-L5 lumbar segment compared to the intact model.
文摘Orthopedic fixation devices are widely used in treatment of spinal diseases. It is expected thatapplication of dynamic stabilization confers valuable movement possibility besides its main role ofload bearing. Comparative investigation between pedicle screw model rigid fixation and (B Dyne,Elaspine, Bioflex, Coflex rivet) models dynamic fixation systems may elucidate the efficacy of eachdesign. The goal of the present study is to evaluate the efficacy of five fixation systems mounted onL4-L5 motion segment. In this numerical study, a 3D precious model of L4, L5 and their intervertebraldisc has been employed based on CT images. Five fixation devices have been also implantedinternally to the motion segment. Finite element method was used to evaluate stress distribution inthe disc and determine the overall displacement of the segment as a measure of movement possibility.The results show that the Coflex rivet implantation can provide stability in all motions and reduce discannulus stress at the surgical segment L4-L5. On the other hand, maximum stress in the disc has beenobserved in dynamic systems but within the safe range. The greater movement of the motion segmenthas also appeared in dynamic fixations. Existence of the fixation systems reduced the stress on theintervertebral disc which might be exerted in intact cases. Use of the fixation devices can considerablyreduce the load on the discs and prepare conditions for healing of the injured ones. Furthermore,dynamic modes of fixation confer possibility of movement to the motion segments in order tofacilitate the spinal activities.
