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The Change of Sagittal Alignment of the Lumbar Spine after Dynesys Stabilization and Proposal of a Refinement
OBJECTIVE: Dynesys® is one of the pedicle-based dynamic lumbar stabilization systems and good clinical outcome has been reported. However, the cylindrical spacer between the heads of the screws undergoes deformation during assembly of the system. The pre-strain probably change the angle of instrumen...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Korean Neurosurgical Society
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4534738/ https://www.ncbi.nlm.nih.gov/pubmed/26279812 http://dx.doi.org/10.3340/jkns.2015.58.1.43 |
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author | Park, Won Man Kim, Chi Heon Kim, Yoon Hyuk Chung, Chun Kee Jahng, Tae-Ahn |
author_facet | Park, Won Man Kim, Chi Heon Kim, Yoon Hyuk Chung, Chun Kee Jahng, Tae-Ahn |
author_sort | Park, Won Man |
collection | PubMed |
description | OBJECTIVE: Dynesys® is one of the pedicle-based dynamic lumbar stabilization systems and good clinical outcome has been reported. However, the cylindrical spacer between the heads of the screws undergoes deformation during assembly of the system. The pre-strain probably change the angle of instrumented spine with time and oblique-shaped spacer may reduce the pre-strain. We analyzed patients with single-level stabilization with Dynesys® and simulated oblique-shaped spacer with finite element (FE) model analysis. METHODS: Consecutive 14 patients, who underwent surgery for single-level lumbar spinal stenosis and were followed-up more than 24 months (M : F=6 : 8; age, 58.7±8.0 years), were analyzed. Lumbar lordosis and segmental angle at the index level were compared between preoperation and postoperative month 24. The von Mises stresses on the obliquely-cut spacer (5°, 10°, 15°, 20°, 25°, and 30°) were calculated under the compressive force of 400 N and 10 Nm of moment with validated FE model of the L4-5 spinal motion segment with segmental angle of 16°. RESULTS: Lumbar lordosis was not changed, while segmental angle was changed significantly from -8.1±7.2° to -5.9±6.7° (p<0.01) at postoperative month 24. The maximum von Mises stresses were markedly decreased with increased angle of the spacer up to 20°. The stress on the spacer was uneven with cylindrical spacer but it became even with the 15° oblique spacer. CONCLUSION: The decreased segmental lordosis may be partially related to the pre-strain of Dynesys. Further clinical and biomechanical studies are required for relevant use of the system. |
format | Online Article Text |
id | pubmed-4534738 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | The Korean Neurosurgical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-45347382015-08-16 The Change of Sagittal Alignment of the Lumbar Spine after Dynesys Stabilization and Proposal of a Refinement Park, Won Man Kim, Chi Heon Kim, Yoon Hyuk Chung, Chun Kee Jahng, Tae-Ahn J Korean Neurosurg Soc Clinical Article OBJECTIVE: Dynesys® is one of the pedicle-based dynamic lumbar stabilization systems and good clinical outcome has been reported. However, the cylindrical spacer between the heads of the screws undergoes deformation during assembly of the system. The pre-strain probably change the angle of instrumented spine with time and oblique-shaped spacer may reduce the pre-strain. We analyzed patients with single-level stabilization with Dynesys® and simulated oblique-shaped spacer with finite element (FE) model analysis. METHODS: Consecutive 14 patients, who underwent surgery for single-level lumbar spinal stenosis and were followed-up more than 24 months (M : F=6 : 8; age, 58.7±8.0 years), were analyzed. Lumbar lordosis and segmental angle at the index level were compared between preoperation and postoperative month 24. The von Mises stresses on the obliquely-cut spacer (5°, 10°, 15°, 20°, 25°, and 30°) were calculated under the compressive force of 400 N and 10 Nm of moment with validated FE model of the L4-5 spinal motion segment with segmental angle of 16°. RESULTS: Lumbar lordosis was not changed, while segmental angle was changed significantly from -8.1±7.2° to -5.9±6.7° (p<0.01) at postoperative month 24. The maximum von Mises stresses were markedly decreased with increased angle of the spacer up to 20°. The stress on the spacer was uneven with cylindrical spacer but it became even with the 15° oblique spacer. CONCLUSION: The decreased segmental lordosis may be partially related to the pre-strain of Dynesys. Further clinical and biomechanical studies are required for relevant use of the system. The Korean Neurosurgical Society 2015-07 2015-07-31 /pmc/articles/PMC4534738/ /pubmed/26279812 http://dx.doi.org/10.3340/jkns.2015.58.1.43 Text en Copyright © 2015 The Korean Neurosurgical Society http://creativecommons.org/licenses/by-nc/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Clinical Article Park, Won Man Kim, Chi Heon Kim, Yoon Hyuk Chung, Chun Kee Jahng, Tae-Ahn The Change of Sagittal Alignment of the Lumbar Spine after Dynesys Stabilization and Proposal of a Refinement |
title | The Change of Sagittal Alignment of the Lumbar Spine after Dynesys Stabilization and Proposal of a Refinement |
title_full | The Change of Sagittal Alignment of the Lumbar Spine after Dynesys Stabilization and Proposal of a Refinement |
title_fullStr | The Change of Sagittal Alignment of the Lumbar Spine after Dynesys Stabilization and Proposal of a Refinement |
title_full_unstemmed | The Change of Sagittal Alignment of the Lumbar Spine after Dynesys Stabilization and Proposal of a Refinement |
title_short | The Change of Sagittal Alignment of the Lumbar Spine after Dynesys Stabilization and Proposal of a Refinement |
title_sort | change of sagittal alignment of the lumbar spine after dynesys stabilization and proposal of a refinement |
topic | Clinical Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4534738/ https://www.ncbi.nlm.nih.gov/pubmed/26279812 http://dx.doi.org/10.3340/jkns.2015.58.1.43 |
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