The effects of tether pretension within vertebral body tethering on the biomechanics of the spine: a Finite Element analysis

Nicolini, Luis Fernando; Greven, Johannes; Kobbe, Philipp; Hildebrand, Frank; Stoffel, Marcus; Markert, Bernd; Yllera, Borja Martinez; Simões, Marcelo Simoni; Roesler, Carlos Rodrigo de Mello; Fancello, Eduardo Alberto

doi:10.1590/1679-78256932

Cited by 4 publications

(4 citation statements)

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“…We utilized a CT image-derived L4-L5 geometry that was manually reconstructed. This geometry was employed in a previously published study by Nicolini et al (2022b) . We scaled this geometry using average dimensions ( Figure 1 ) from various experiments in the literature ( Shirazi-Adl, 1994 ; Schmidt et al, 2006 ; Little et al, 2008 ; Kiapour et al, 2009 ; Zander et al, 2009 ; Busscher et al, 2010 ; Ayturk and Puttlitz, 2011 ; Liu et al, 2011 ; Park et al, 2013 ; Jaramillo et al, 2015 ; Bashkuev et al, 2020 ; Nicolini et al, 2022a ).…”

Section: Methodsmentioning

confidence: 99%

“…This hyperelastic material model is derived from the strain energy density function as described in Eq. 1 ( Freutel et al, 2014 ; Nicolini et al, 2022b ):

The stiffness and compressibility of the matrix are determined by the material parameters C 10 , C 01 , and D . J α defines the elastic volume strain, and I 1 and I 2 represent the first and second invariants of the right Cauchy-Green deformation tensor.…”

Section: Methodsmentioning

confidence: 99%

“…We conducted a mesh sensitivity study to choose appropriate mesh parameters that provide precise outcomes without significantly increasing the computational time. This analysis was based on the previous study from Nicolini et al (2022b) . We applied a pure moment load of 5 Nm in flexion and examined the outcomes for range of motion (RoM) and the simulation time across different mesh sizes and shape functions using hexahedral elements.…”

Section: Methodsmentioning

confidence: 99%

“…This hyperelastic material model is derived from the strain energy density function as described in Eq. 1 (Freutel et al, 2014;Nicolini et al, 2022b):…”

Section: Finite Element Modelsmentioning

confidence: 99%

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Comparative FEM study on intervertebral disc modeling: Holzapfel-Gasser-Ogden vs. structural rebars

Gruber,

Nicolini,

Ribeiro

et al. 2024

Front. Bioeng. Biotechnol.

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Introduction: Numerical modeling of the intervertebral disc (IVD) is challenging due to its complex and heterogeneous structure, requiring careful selection of constitutive models and material properties. A critical aspect of such modeling is the representation of annulus fibers, which significantly impact IVD biomechanics. This study presents a comparative analysis of different methods for fiber reinforcement in the annulus fibrosus of a finite element (FE) model of the human IVD.Methods: We utilized a reconstructed L4-L5 IVD geometry to compare three fiber modeling approaches: the anisotropic Holzapfel-Gasser-Ogden (HGO) model (HGO fiber model) and two sets of structural rebar elements with linear-elastic (linear rebar model) and hyperelastic (nonlinear rebar model) material definitions, respectively. Prior to calibration, we conducted a sensitivity analysis to identify the most important model parameters to be calibrated and improve the efficiency of the calibration. Calibration was performed using a genetic algorithm and in vitro range of motion (RoM) data from a published study with eight specimens tested under four loading scenarios. For validation, intradiscal pressure (IDP) measurements from the same study were used, along with additional RoM data from a separate publication involving five specimens subjected to four different loading conditions.Results: The sensitivity analysis revealed that most parameters, except for the Poisson ratio of the annulus fibers and C01 from the nucleus, significantly affected the RoM and IDP outcomes. Upon calibration, the HGO fiber model demonstrated the highest accuracy (R2 = 0.95), followed by the linear (R2 = 0.89) and nonlinear rebar models (R2 = 0.87). During the validation phase, the HGO fiber model maintained its high accuracy (RoM R2 = 0.85; IDP R2 = 0.87), while the linear and nonlinear rebar models had lower validation scores (RoM R2 = 0.71 and 0.69; IDP R2 = 0.86 and 0.8, respectively).Discussion: The results of the study demonstrate a successful calibration process that established good agreement with experimental data. Based on our findings, the HGO fiber model appears to be a more suitable option for accurate IVD FE modeling considering its higher fidelity in simulation results and computational efficiency.

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Section: Methodsmentioning

confidence: 99%

“…This hyperelastic material model is derived from the strain energy density function as described in Eq. 1 ( Freutel et al, 2014 ; Nicolini et al, 2022b ):

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…This hyperelastic material model is derived from the strain energy density function as described in Eq. 1 (Freutel et al, 2014;Nicolini et al, 2022b):…”

Section: Finite Element Modelsmentioning

confidence: 99%

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