Biomechanical analysis of lumbar fusion with proximal interspinous process device implantation

Abstract

Lumbar spinal fusion may cause adjacent segment degeneration (ASD) in the long term. Recently, inserting an interspinous process device (IPD) proximal to the fusion has been proposed to prevent ASD. The aim of this study was to investigate the biomechanics of lumbar fusion with proximal IPD implantation (LFPI) under both static loads and whole body vibration (WBV). A previously validated finite element (FE) model of the L1‐5 lumbar spine was modified to simulate L4‐5 fusion. Three different IPDs (Coflex‐F, Wallis and DIAM) were inserted at the L3‐4 segment of the fusion model to construct the LFPI models. The intact and surgical FE models were analyzed under static loads and WBV, respectively. Under static loading conditions, LFPI decreased range of motion (ROM) and intradiscal pressure (IDP) at the transition segment L3‐4 compared with the fusion case. At the segment (L2‐3) adjacent to the transition level, LFPI induced higher motion and IDP than rigid fusion. Under WBV, vibration amplitudes of the L3‐4 IDP and L4‐5 facet joint force (FJF) decreased by more than 54.3% after surgery. The LFPI model with the DIAM system offered the most comparable biomechanics to the intact model under static loads, and decreased the dynamic responses of the L4‐5 FJF under WBV. The LFPI model with the Wallis and Coflex‐F systems could stabilize the transition segment, and decrease dynamic responses of the L3‐4 IDP. The DIAM system may be more suitable in LFPI.

Biomechanical analysis of lumbar nonfusion dynamic stabilization using a pedicle screw‐based dynamic stabilizer or an interspinous process spacer

“…Mesh convergence analysis was conducted by refining the mesh size to consecutively generate mesh resolutions, until the tolerance is less than 1% between two consecutive mesh resolutions. The material properties derived from the published literature 22,[25][26][27][28][29][30][31] and mesh element types for each component in the models are listed in Table 1.…”

“…Because the present surgical models were designed to simulate the biomechanical behavior of long-term effects after instrumentation, the implant-bone interfaces were assumed to be completely bonded via node sharing. 26,29 All the models were fully fixed at sacrum and were subjected to a compressive follower preload of 400 N. Furthermore, additional static loading and vibration loading were applied to these models, respectively.…”

Determining a relative total lumbar range of motion to alleviate adjacent segment degeneration after transforaminal lumbar interbody fusion: a finite element analysis

“…The reduced ROM of the fixed segment is compensated by other segments to restore the overall motor function of the spine, which can lead to an abnormal increase in IDP and FJF [ 10 ]. Thus, the published literature has mainly focused on reducing ROM, IDP, and FJF to alleviate ASD by improving surgical techniques, such as semirigid fixation and dynamic fixation [ 11 – 13 ]. However, few studies have addressed this issue from the perspective of postoperative waist activities.…”

Prediction of the biomechanical behaviour of the lumbar spine under multi‐axis whole‐body vibration using a whole‐body finite element model

“…Therefore, the FE method is often used to predict the internal biomechanical responses of the human body. To date, many FE models have been developed to analyse the biomechanical characteristics of the human body, and have obtained meaningful results 24–30 . Some studies have also analysed the mechanical behaviour of IVD made of shape memory polymers and their possible use in total disc replacement 31,32 .…”

“…To date, many FE models have been developed to analyse the biomechanical characteristics of the human body, and have obtained meaningful results. [24][25][26][27][28][29][30] Some studies have also analysed the mechanical behaviour of IVD made of shape memory polymers and their possible use in total disc replacement. 31,32 In this study, a whole-body FE model was used to provide the possibility of obtaining internal spinal loads in a wholebody environment.…”