A patient specific computational biomechanical model for the entire lumbosacral spinal unit with imposed spondylolysis

Haj-Ali, Rami; Wolfson, Roza; Masharawi, Youssef

doi:10.1016/j.clinbiomech.2019.05.022

Cited by 6 publications

(4 citation statements)

References 16 publications

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“…The current time required to create a FE model of the spine is rarely reported but the state-ofthe-art process includes using a software for the segmentation of volumetric images to obtain surface meshes. The latter are again imported in a second software to create volumetric models and perform the FE simulations including pre-and postprocessing steps (Bah et al, 2009;Haj-Ali et al, 2019;Jiang and Li, 2019;Özmen and Günay, 2019). From our empirical experience, the process of segmentation, meshing, FE model preparation and simulation can take up to several days.…”

Section: Discussionmentioning

confidence: 99%

“…The cropping itself represents a very quick step for medical professionals and the pipeline functions with different cropping sizes and regions of the lumbar spine. This is one of the main differences to other semi-automatic approaches consisting of labor-intensive (and therefore costly) and time-consuming steps (Zadpoor and Weinans, 2015;Haj-Ali et al, 2019;Nikkhoo et al, 2020). Indeed, many training data used in this work were manually annotated, for example the segmentation of 3D CT images, or the anatomical landmarks defined on the reference meshes of the SSMs.…”

Section: Discussionmentioning

confidence: 99%

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Automated Pipeline to Generate Anatomically Accurate Patient-Specific Biomechanical Models of Healthy and Pathological FSUs

Caprara

Carrillo

Snedeker

et al. 2021

Front. Bioeng. Biotechnol.

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State-of-the-art preoperative biomechanical analysis for the planning of spinal surgery not only requires the generation of three-dimensional patient-specific models but also the accurate biomechanical representation of vertebral joints. The benefits offered by computational models suitable for such purposes are still outweighed by the time and effort required for their generation, thus compromising their applicability in a clinical environment. In this work, we aim to ease the integration of computerized methods into patient-specific planning of spinal surgery. We present the first pipeline combining deep learning and finite element methods that allows a completely automated model generation of functional spine units (FSUs) of the lumbar spine for patient-specific FE simulations (FEBio). The pipeline consists of three steps: (a) multiclass segmentation of cropped 3D CT images containing lumbar vertebrae using the DenseVNet network, (b) automatic landmark-based mesh fitting of statistical shape models onto 3D semantic segmented meshes of the vertebral models, and (c) automatic generation of patient-specific FE models of lumbar segments for the simulation of flexion-extension, lateral bending, and axial rotation movements. The automatic segmentation of FSUs was evaluated against the gold standard (manual segmentation) using 10-fold cross-validation. The obtained Dice coefficient was 93.7% on average, with a mean surface distance of 0.88 mm and a mean Hausdorff distance of 11.16 mm (N = 150). Automatic generation of finite element models to simulate the range of motion (ROM) was successfully performed for five healthy and five pathological FSUs. The results of the simulations were evaluated against the literature and showed comparable ROMs in both healthy and pathological cases, including the alteration of ROM typically observed in severely degenerated FSUs. The major intent of this work is to automate the creation of anatomically accurate patient-specific models by a single pipeline allowing functional modeling of spinal motion in healthy and pathological FSUs. Our approach reduces manual efforts to a minimum and the execution of the entire pipeline including simulations takes approximately 2 h. The automation, time-efficiency and robustness level of the pipeline represents a first step toward its clinical integration.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Automated Pipeline to Generate Anatomically Accurate Patient-Specific Biomechanical Models of Healthy and Pathological FSUs

Caprara

Carrillo

Snedeker

et al. 2021

Front. Bioeng. Biotechnol.

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“…This also suggests that lumbar spondylolysis can lead to decreased spine stability, and long-term instability can lead to vertebral spondylolisthesis. Moreover, combined with the results of intervertebral disc stress analysis, it can be concluded that changes in activity can lead to the biomechanical imbalance of relevant segments, instantaneous rotation center deviation, increased intervertebral disc tissue stress, and risk of degeneration (Sairyo et al, 2006c;Haj-Ali et al, 2019). Compared with Model B, the ROM and maximum displacement of Model C, D, and E decreased due to the addition of an internal fixation device.…”

Section: Figurementioning

confidence: 99%

“…However, the above two fixation methods also have certain defects. For example, although the Buck technique can fix the isthmus directly, it cannot solve the problem of stress concentration in the lumbosacral region (Sairyo et al, 2006a;Sterba et al, 2018;Haj-Ali et al, 2019). On the other hand, the pedicle screw technique can disperse stress from the lumbosacral region, but it cannot ensure isthmus stability.…”

Section: Introductionmentioning

confidence: 99%

Biomechanical evaluation of lumbar spondylolysis repair with various fixation options: A finite element analysis

Jin²,

Yang³

et al. 2022

Front. Bioeng. Biotechnol.

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Objective: This study was designed to compare the biomechanical properties of lumbar spondylolysis repairs using different fixation methods by using three-dimensional finite element analysis.Methods: Five finite element models (A, B, C, D, and E) of L4-S1 vertebral body were reconstructed by CT images of a male patient (A: intact model; B: spondylolysis model; C: spondylolysis model with intrasegmental direct fixation by Buck screw; D: spondylolysis model with intersegmental indirect fixation by pedicle screw system; E: spondylolysis model with hybrid internal fixation). L5-S1 level was defined as the operative level. After the intact model was verified, six physiological motion states were simulated by applying 500 N concentrated force and 10 Nm torque on the upper surface of L4. The biomechanical properties of the three different internal fixation methods were evaluated by comparing the range of motion (ROM), maximum stress, and maximum displacement.Results: Compared with Model B, the ROM and maximum displacement of Model C, D, and E decreased. The maximum stress on L5/S1 disc in models A, B, and C was much higher than that in Model D and E under extension and lateral bending conditions. Under axial rotation and lateral bending conditions, the maximum stress of interarticular muscle and internal fixation system in Model B and Model C was significantly higher than that in Model D and Model E. In contrast to Model D, the stress in Model E was distributed in two internal fixation systems.Conclusion: In several mechanical comparisons, hybrid fixation had better biomechanical properties than other fixation methods. The experimental results show that hybrid fixation can stabilize the isthmus and reduce intervertebral disc stress, which making it the preferred treatment for lumbar spondylolysis.

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Recent Developments in Finite Element Analysis of the Lumbar Spine

Khuyagbaatar

Kim

2023

Int. J. Precis. Eng. Manuf.

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A patient specific computational biomechanical model for the entire lumbosacral spinal unit with imposed spondylolysis

Cited by 6 publications

References 16 publications

Automated Pipeline to Generate Anatomically Accurate Patient-Specific Biomechanical Models of Healthy and Pathological FSUs

Automated Pipeline to Generate Anatomically Accurate Patient-Specific Biomechanical Models of Healthy and Pathological FSUs

Biomechanical evaluation of lumbar spondylolysis repair with various fixation options: A finite element analysis

Recent Developments in Finite Element Analysis of the Lumbar Spine

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