Page 31 - חוברת תזות הנדסה ירוקה 2024

Patient-specific 3D-printed implant using finite element analysis
David Blyaher; dovidb90@gmail.com Dr. Trabelsi Nir, Dr. Trubovich Zuk
Sami Shamoon College of Engineering, Beer-Sheva, Israel.
The field of orthopedic implants is rapidly expanding due to longer lifespans and changing lifestyles. Currently, standardized manufacturing processes for implants leads to increased wear and associated risks. Recently, a shift towards custom implants has emerged, optimizing weight, geometry, stress dissipation, and stress shielding.
This customized technology offers potential benefits, like shorter surgeries, quicker recoveries, improved success rates, and longer-lasting implants.
3D-printing technology presents the opportunity to produce patient-specific implants with great ease. In most cases, a geometrical fitting process is used; however, the further implementation of analytical tools, such as finite element analysis during the design phase can enhance implant optimization.
This primary focus of this research is the study of the mechanical behavior of spine units with varying intervertebral disc )IVD( degeneration levels and custom 3D-printed IVDs.
The present study consists of multiple steps. In the first stage, utilizes CT scans for segmentation, followed modeling via MATLAB to comprehensively segment the vertebrae, then CAD software creates 3D models of vertebrae and IVDs at different levels of degeneration and of a custom-made disc. These models are then subjected to finite element analysis using “Abaqus“ software, that reveals correlations between IVD degeneration, loads, displacements, and stress dissipation.
The finite element models employing Mooney-Rivlin hyperelastic material for the IVD and to simulate ligaments as nonlinear, unidirectional springs under various physiological loads )flexion, extension, lateral bending, and axial rotation(.
In the second stage, a compression test is conducted on five printed IVDs with different geometries and orientations, to determine the optimal geometry. The selected disc is subsequently used to assess material properties for further analyses. The compression shows the importance of printing orientation )in FDM( on the mechanical behavior and thus the ability to better match the IVD to the patient lifestyle. Additionally in thevertical printed IVDs a buckling process was spotted instead of the layer separation that was expected.
To gain comprehensive understanding of spinal reactions to varying loads, a compression experiment was conducted on a donor L1-S1 spine unit in collaboration with Prof. Zohar Yossibash from Tel-Aviv University’s School of Mechanical Engineering. This series of static compression tests, employing different moments, exhibited consistent results and large deformation. Accurate measurement of strains and displacements was achieved through digital image correlation, providing crucial data for the validation of the finite element model.
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