Methods of Segmental Screw Fixation of Axis: A Cadaveric and Surgical Study

Background Data: Axis fixation is still challenging due to intimate relation with the vertebral artery and complex topographical anatomy. Purpose: The aim of this work is to assess and compare the safety, feasibility and limitations of 3 posterior segmental axis fixation techniques (transpedicular,...

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Autor principal:	Mohamed El-Gaidi
Formato:	article
Lenguaje:	EN
Publicado:	Egyptian Spine Association 2016
Materias:	Axis Fixation Trans-laminar Transpars-interarticularis Transpedicular screws Atlantoaxial Instability Neurology. Diseases of the nervous system RC346-429
Acceso en línea:	https://doaj.org/article/e491dae438d84bdaa1be207917ad7160
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spelling	oai:doaj.org-article:e491dae438d84bdaa1be207917ad71602021-12-02T03:08:52ZMethods of Segmental Screw Fixation of Axis: A Cadaveric and Surgical StudyDOI:10.21608/ESJ.2016.39852314-89502314-8969https://doaj.org/article/e491dae438d84bdaa1be207917ad71602016-04-01T00:00:00Zhttp://www.esj.journals.ekb.eg/article_3985.htmlhttps://doaj.org/toc/2314-8950https://doaj.org/toc/2314-8969Background Data: Axis fixation is still challenging due to intimate relation with the vertebral artery and complex topographical anatomy. Purpose: The aim of this work is to assess and compare the safety, feasibility and limitations of 3 posterior segmental axis fixation techniques (transpedicular, transpars and translaminar screws). Study Design: A retrospective anatomico-radiological study. Material and Methods: Forty axis vertebrae (27 dry bone and 13 computed tomography scans of patients who underwent axis fixation) were retrospectively studied (total 80 sides). The morphology of the pedicle, pars interarticularis and lamina were assessed bilaterally for the width (W), height (H) and screw length (L). In addition, the spino-laminar angle was measured. It was considered difficult for a conventional 3.5mm screw to be inserted safely, if any of these parameters is ≤4.5mm. Results: The mean pedicle, pars and lamina W and H were (6.0±1.5mm and 7.1±1.8mm), (9.51.6±mm and 192.5±mm) and (6.21.5±mm and 12.1±1.5mm) respectively. The mean spino-laminar angle was 45.1±4° laterally. The mean transpedicular and translaminar screw lengths were 26.8±2.2 and 23±4.1mm respectively. While the feasibility rates were 83.7% and 90% because the pedicle (W and H) and laminar (W) were ≤4.5mm respectively. All the pars measured in this study can tolerate a 14mm screw. However, when using 15mm, 16mm, 17mm and 18mm screws, the incidence of violating the vertebral artery groove was 2.5%, 6.3%, 13.8% and 23.8% respectively. Conclusion: Transpedicular screws provide the most rigid fixation (longest screws), however in case of high vertebral groove, translaminar screws are better option rather than transpars screws except in small size laminae. (2016ESJ094) Mohamed El-GaidiEgyptian Spine AssociationarticleAxis FixationTrans-laminarTranspars-interarticularisTranspedicular screwsAtlantoaxial InstabilityNeurology. Diseases of the nervous systemRC346-429ENEgyptian Spine Journal, Vol 18, Iss 1, Pp 5-14 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	Axis Fixation Trans-laminar Transpars-interarticularis Transpedicular screws Atlantoaxial Instability Neurology. Diseases of the nervous system RC346-429
spellingShingle	Axis Fixation Trans-laminar Transpars-interarticularis Transpedicular screws Atlantoaxial Instability Neurology. Diseases of the nervous system RC346-429 Mohamed El-Gaidi Methods of Segmental Screw Fixation of Axis: A Cadaveric and Surgical Study
description	Background Data: Axis fixation is still challenging due to intimate relation with the vertebral artery and complex topographical anatomy. Purpose: The aim of this work is to assess and compare the safety, feasibility and limitations of 3 posterior segmental axis fixation techniques (transpedicular, transpars and translaminar screws). Study Design: A retrospective anatomico-radiological study. Material and Methods: Forty axis vertebrae (27 dry bone and 13 computed tomography scans of patients who underwent axis fixation) were retrospectively studied (total 80 sides). The morphology of the pedicle, pars interarticularis and lamina were assessed bilaterally for the width (W), height (H) and screw length (L). In addition, the spino-laminar angle was measured. It was considered difficult for a conventional 3.5mm screw to be inserted safely, if any of these parameters is ≤4.5mm. Results: The mean pedicle, pars and lamina W and H were (6.0±1.5mm and 7.1±1.8mm), (9.51.6±mm and 192.5±mm) and (6.21.5±mm and 12.1±1.5mm) respectively. The mean spino-laminar angle was 45.1±4° laterally. The mean transpedicular and translaminar screw lengths were 26.8±2.2 and 23±4.1mm respectively. While the feasibility rates were 83.7% and 90% because the pedicle (W and H) and laminar (W) were ≤4.5mm respectively. All the pars measured in this study can tolerate a 14mm screw. However, when using 15mm, 16mm, 17mm and 18mm screws, the incidence of violating the vertebral artery groove was 2.5%, 6.3%, 13.8% and 23.8% respectively. Conclusion: Transpedicular screws provide the most rigid fixation (longest screws), however in case of high vertebral groove, translaminar screws are better option rather than transpars screws except in small size laminae. (2016ESJ094)
format	article
author	Mohamed El-Gaidi
author_facet	Mohamed El-Gaidi
author_sort	Mohamed El-Gaidi
title	Methods of Segmental Screw Fixation of Axis: A Cadaveric and Surgical Study
title_short	Methods of Segmental Screw Fixation of Axis: A Cadaveric and Surgical Study
title_full	Methods of Segmental Screw Fixation of Axis: A Cadaveric and Surgical Study
title_fullStr	Methods of Segmental Screw Fixation of Axis: A Cadaveric and Surgical Study
title_full_unstemmed	Methods of Segmental Screw Fixation of Axis: A Cadaveric and Surgical Study
title_sort	methods of segmental screw fixation of axis: a cadaveric and surgical study
publisher	Egyptian Spine Association
publishDate	2016
url	https://doaj.org/article/e491dae438d84bdaa1be207917ad7160
work_keys_str_mv	AT mohamedelgaidi methodsofsegmentalscrewfixationofaxisacadavericandsurgicalstudy
_version_	1718401951643729920

Methods of Segmental Screw Fixation of Axis: A Cadaveric and Surgical Study

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