Nonlinear mechanical analysis of posterior spinal instrumentation for osteoporotic vertebra: Effects of mechanical properties of the rod on the failure risks around the screw
In spinal fusion with instrumentation for the treatment of osteoporotic vertebral fracture, it is common for pedicle screws, which are inserted into vertebrae and strongly immobilized by a rigid rod, to loosen and dissociate. One of their expected causes is failure and reduction of fixity around a s...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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The Japan Society of Mechanical Engineers
2014-06-01
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| Series: | Journal of Biomechanical Science and Engineering |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/jbse/9/2/9_13-00163/_pdf/-char/en |
| _version_ | 1811224001724284928 |
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| author | Daisuke TAWARA Kenta NORO Tetsuya TSUJIKAMI Yoshiyuki OKAMOTO Hideki MURAKAMI |
| author_facet | Daisuke TAWARA Kenta NORO Tetsuya TSUJIKAMI Yoshiyuki OKAMOTO Hideki MURAKAMI |
| author_sort | Daisuke TAWARA |
| collection | DOAJ |
| description | In spinal fusion with instrumentation for the treatment of osteoporotic vertebral fracture, it is common for pedicle screws, which are inserted into vertebrae and strongly immobilized by a rigid rod, to loosen and dissociate. One of their expected causes is failure and reduction of fixity around a screw. An improved rod with a damper structure has thus been proposed to increase the freedom of movement of the rod and allow more flexible fixation of the spine. To evaluate the availability of the proposed structure and establish appropriate improved design of screws and rods with fewer occurrences of loosening and dissociation, effects of the structural change to the improved rod on the distribution of failure risks around the screw need to be investigated. In the present study, we performed nonlinear fracture analysis for spinal instrumentation surgery using an osteoporosis model and evaluated the failure distribution in the vertebrae while changing the apparent stiffness of the damper joint. Our finite element analysis showed that there were few expected failures in the flexible fixation model, indicating the effectiveness of the improved structure of the rod in reducing the loosening and dissociation of screws. It also suggested that the reduction was derived from the allowance of horizontal deformation in the damper joint in the improved rod. The potential of the structural improvement and the mechanism responsible for reducing the risks of loosening and dissociation are discussed. |
| first_indexed | 2024-04-12T08:41:56Z |
| format | Article |
| id | doaj.art-9b356cef32bf49d984a298199a1f3947 |
| institution | Directory Open Access Journal |
| issn | 1880-9863 |
| language | English |
| last_indexed | 2024-04-12T08:41:56Z |
| publishDate | 2014-06-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Journal of Biomechanical Science and Engineering |
| spelling | doaj.art-9b356cef32bf49d984a298199a1f39472022-12-22T03:39:50ZengThe Japan Society of Mechanical EngineersJournal of Biomechanical Science and Engineering1880-98632014-06-019213-0016313-0016310.1299/jbse.13-00163jbseNonlinear mechanical analysis of posterior spinal instrumentation for osteoporotic vertebra: Effects of mechanical properties of the rod on the failure risks around the screwDaisuke TAWARA0Kenta NORO1Tetsuya TSUJIKAMI2Yoshiyuki OKAMOTO3Hideki MURAKAMI4Department of Mechanical and Systems Engineering, Ryukoku UniversityGraduate School of Mechanical and Systems Engineering, Ryukoku UniversityDepartment of Mechanical and Systems Engineering, Ryukoku UniversityDepartment of Orthopedic Surgery, Kanazawa University HospitalDepartment of Orthopedic Surgery, Kanazawa University HospitalIn spinal fusion with instrumentation for the treatment of osteoporotic vertebral fracture, it is common for pedicle screws, which are inserted into vertebrae and strongly immobilized by a rigid rod, to loosen and dissociate. One of their expected causes is failure and reduction of fixity around a screw. An improved rod with a damper structure has thus been proposed to increase the freedom of movement of the rod and allow more flexible fixation of the spine. To evaluate the availability of the proposed structure and establish appropriate improved design of screws and rods with fewer occurrences of loosening and dissociation, effects of the structural change to the improved rod on the distribution of failure risks around the screw need to be investigated. In the present study, we performed nonlinear fracture analysis for spinal instrumentation surgery using an osteoporosis model and evaluated the failure distribution in the vertebrae while changing the apparent stiffness of the damper joint. Our finite element analysis showed that there were few expected failures in the flexible fixation model, indicating the effectiveness of the improved structure of the rod in reducing the loosening and dissociation of screws. It also suggested that the reduction was derived from the allowance of horizontal deformation in the damper joint in the improved rod. The potential of the structural improvement and the mechanism responsible for reducing the risks of loosening and dissociation are discussed.https://www.jstage.jst.go.jp/article/jbse/9/2/9_13-00163/_pdf/-char/enorthopedic computational biomechanicsspinal instrumentationnonlinear analysisloosening of screwosteoporosis |
| spellingShingle | Daisuke TAWARA Kenta NORO Tetsuya TSUJIKAMI Yoshiyuki OKAMOTO Hideki MURAKAMI Nonlinear mechanical analysis of posterior spinal instrumentation for osteoporotic vertebra: Effects of mechanical properties of the rod on the failure risks around the screw Journal of Biomechanical Science and Engineering orthopedic computational biomechanics spinal instrumentation nonlinear analysis loosening of screw osteoporosis |
| title | Nonlinear mechanical analysis of posterior spinal instrumentation for osteoporotic vertebra: Effects of mechanical properties of the rod on the failure risks around the screw |
| title_full | Nonlinear mechanical analysis of posterior spinal instrumentation for osteoporotic vertebra: Effects of mechanical properties of the rod on the failure risks around the screw |
| title_fullStr | Nonlinear mechanical analysis of posterior spinal instrumentation for osteoporotic vertebra: Effects of mechanical properties of the rod on the failure risks around the screw |
| title_full_unstemmed | Nonlinear mechanical analysis of posterior spinal instrumentation for osteoporotic vertebra: Effects of mechanical properties of the rod on the failure risks around the screw |
| title_short | Nonlinear mechanical analysis of posterior spinal instrumentation for osteoporotic vertebra: Effects of mechanical properties of the rod on the failure risks around the screw |
| title_sort | nonlinear mechanical analysis of posterior spinal instrumentation for osteoporotic vertebra effects of mechanical properties of the rod on the failure risks around the screw |
| topic | orthopedic computational biomechanics spinal instrumentation nonlinear analysis loosening of screw osteoporosis |
| url | https://www.jstage.jst.go.jp/article/jbse/9/2/9_13-00163/_pdf/-char/en |
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