Stress Distribution and Strain Analysis of LAR and RAR Intervertebral Cages Using the Finite Element Method
محورهای موضوعی : Analytical and Numerical Methods in Mechanical Design
Golrokh Amin alizadeh
1
,
Behzad Yasrebi
2
,
Mehdi Razeghi
3
1 - Department of Biomedical engineering, SR.C., Islamic Azad University,Tehran, Iran.
2 - Department of Biomedical engineering, Ta.c., Islamic Azad University, Tabriz, Iran
3 - Department of Biomedical Engineering, SR.C., Islamic Azad University, Tehran, Iran
کلید واژه: Modeling, Interbody cage, Finite element method, Lumbar spine, Strain, Stress, Biomechanical analysis.,
چکیده مقاله :
The accuracy of biomechanics analyses based on the finite element method in biological structures strongly depends on precise geometric modeling and the correct definition of tissue mechanical properties. The aim of this study was to investigate and compare the stress and strain distributions in two types of lumber interbody cages, LAR and RAR, using theoretical analysis and finite element modeling. For three-dimensional reconstruction, lumbar vertebrae were generated from CT scan data, and complete models of the vertebrae and cages were developed. Finite element analysis was performed in MSC Nastran under physiologic loading conditions. The results demonstrated that the LAR cage, due to its polymeric material and geometric design, produced more uniform stress distribution and lower strain in contact regions, offering greater stability compared with the titanium RAR cage. In contrast, the RAR cage exhibited higher stress concentration and a stiffer mechanical response, which may increase the risk of subsidence and mechanical mismatch with the bone. These findings indicate that cage material and geometry play a critical role in load transmission, stress reduction, and improving the mechanical performance of fusion constructs. The results of this study can assist in optimizing the design and selection of interbody cages with improved biomechanical performance and enhanced biocompatibility.
The accuracy of biomechanics analyses based on the finite element method in biological structures strongly depends on precise geometric modeling and the correct definition of tissue mechanical properties. The aim of this study was to investigate and compare the stress and strain distributions in two types of lumber interbody cages, LAR and RAR, using theoretical analysis and finite element modeling. For three-dimensional reconstruction, lumbar vertebrae were generated from CT scan data, and complete models of the vertebrae and cages were developed. Finite element analysis was performed in MSC Nastran under physiologic loading conditions. The results demonstrated that the LAR cage, due to its polymeric material and geometric design, produced more uniform stress distribution and lower strain in contact regions, offering greater stability compared with the titanium RAR cage. In contrast, the RAR cage exhibited higher stress concentration and a stiffer mechanical response, which may increase the risk of subsidence and mechanical mismatch with the bone. These findings indicate that cage material and geometry play a critical role in load transmission, stress reduction, and improving the mechanical performance of fusion constructs. The results of this study can assist in optimizing the design and selection of interbody cages with improved biomechanical performance and enhanced biocompatibility.
1. Rohlmann A, Zander T, Schmidt H. Effect of implant stiffness on stress distribution in the lumbar spine: A finite element analysis..Clinical Biomechanics. 2018;53:85-92
2. Yue J,Zhao Q, Wang Y. Finite element analysis of different interbody cage designs in lumbar.fusion. Spine Journal. 2019;19(2):215-224
3. Liu Z, Chen J, Wu T. Influence of cage geometry and material on
stress distribution in lumbar interbody fusion: A FEM study. Journal of Orthopaedic Research..2020;38(5):1038-1046.
4. Kurtz SM, Devine JN. PEEK biomaterials in trauma, orthopedic, and spinal implants. .Biomaterials. 2019;31(4):631-640
5. Goel VK, Kong W, Han JS. Biomechanical testing of the spine: load-displacement characteristics for different spinal levels..Spine. 2017;12(7):569-577
6. Shirazi-Adl A, Ahmed AM, Shrivastava SC. A finite element study of a lumbar motion segment subjected to pure sagittal plane moments. Journal of Biomechanics..1986;19(4):331-350
7. Oxland TR, Lund T. Biomechanics of interbody devices and bone grafts. Spine..2019;25(23):2940-2947
8. Chen SH, Lin SC, Tsai WC. Stress analysis of the spine using finite element modeling. Medical Engineering & Physics..2018;40(3):83-91
9. Frost HM. Bones mechanostat: A 2003 update. Anatomical Record..2003;275(2):1081-1101
10. Brantigan JW, Steffee AD. A carbon fiber implant to aid interbody lumbar fusion. Spine..1993;18(14):2106-2117
11. Zdeblick TA, Phillips FM. Interbody cage.devices. Spine Journal. 2003;3(2):95-99
