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Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population

STUDY DESIGN: Computed tomographic (CT) morphometric analysis. PURPOSE: To assess the feasibility and safety of occipital condyle (OC)-based occipitocervical fixation (OCF) in Indians and to define anatomical zones and screw lengths for safe screw placement. OVERVIEW OF LITERATURE: Limitations of oc...

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Autores principales: Bosco, Aju, Venugopal, Prakash, Shetty, Ajoy Prasad, Shanmuganathan, Rajasekaran, Kanna, Rishi Mugesh
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Korean Society of Spine Surgery 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913011/
https://www.ncbi.nlm.nih.gov/pubmed/29713401
http://dx.doi.org/10.4184/asj.2018.12.2.214
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author Bosco, Aju
Venugopal, Prakash
Shetty, Ajoy Prasad
Shanmuganathan, Rajasekaran
Kanna, Rishi Mugesh
author_facet Bosco, Aju
Venugopal, Prakash
Shetty, Ajoy Prasad
Shanmuganathan, Rajasekaran
Kanna, Rishi Mugesh
author_sort Bosco, Aju
collection PubMed
description STUDY DESIGN: Computed tomographic (CT) morphometric analysis. PURPOSE: To assess the feasibility and safety of occipital condyle (OC)-based occipitocervical fixation (OCF) in Indians and to define anatomical zones and screw lengths for safe screw placement. OVERVIEW OF LITERATURE: Limitations of occipital squama-based OCF has led to development of two novel OC-based OCF techniques. METHODS: Morphometric analysis was performed on the OCs of 70 Indian adults. The feasibility of placing a 3.5-mm-diameter screw into OCs was investigated. Safe trajectories and screw lengths for OC screws and C0–C1 transarticular screws without hypoglossal canal or atlantooccipital joint compromise were estimated. RESULTS: The average screw length and safe sagittal and medial angulations for OC screws were 19.9±2.3 mm, ≤6.4°±2.4° cranially, and 31.1°±3° medially, respectively. An OC screw could not be accommodated by 27% of the population. The safe sagittal angles and screw lengths for C0–C1 transarticular screw insertion (48.9°±5.7° cranial, 26.7±2.9 mm for junctional entry technique; 36.7°±4.6° cranial, 31.6±2.7 mm for caudal C1 arch entry technique, respectively) were significantly different than those in other populations. The risk of vertebral artery injury was high for the caudal C1 arch entry technique. Screw placement was uncertain in 48% of Indians due to the presence of aberrant anatomy. CONCLUSIONS: There were significant differences in the metrics of OC-based OCF between Indian and other populations. Because of the smaller occipital squama dimensions in Indians, OC-based OCF techniques may have a higher application rate and could be a viable alternative/salvage option in selected cases. Preoperative CT, including three-dimensional-CT-angiography (to delineate vertebral artery course), is imperative to avoid complications resulting from aberrant bony and vascular anatomy. Our data can serve as a valuable reference guide in placing these screws safely under fluoroscopic guidance.
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spelling pubmed-59130112018-04-30 Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population Bosco, Aju Venugopal, Prakash Shetty, Ajoy Prasad Shanmuganathan, Rajasekaran Kanna, Rishi Mugesh Asian Spine J Clinical Study STUDY DESIGN: Computed tomographic (CT) morphometric analysis. PURPOSE: To assess the feasibility and safety of occipital condyle (OC)-based occipitocervical fixation (OCF) in Indians and to define anatomical zones and screw lengths for safe screw placement. OVERVIEW OF LITERATURE: Limitations of occipital squama-based OCF has led to development of two novel OC-based OCF techniques. METHODS: Morphometric analysis was performed on the OCs of 70 Indian adults. The feasibility of placing a 3.5-mm-diameter screw into OCs was investigated. Safe trajectories and screw lengths for OC screws and C0–C1 transarticular screws without hypoglossal canal or atlantooccipital joint compromise were estimated. RESULTS: The average screw length and safe sagittal and medial angulations for OC screws were 19.9±2.3 mm, ≤6.4°±2.4° cranially, and 31.1°±3° medially, respectively. An OC screw could not be accommodated by 27% of the population. The safe sagittal angles and screw lengths for C0–C1 transarticular screw insertion (48.9°±5.7° cranial, 26.7±2.9 mm for junctional entry technique; 36.7°±4.6° cranial, 31.6±2.7 mm for caudal C1 arch entry technique, respectively) were significantly different than those in other populations. The risk of vertebral artery injury was high for the caudal C1 arch entry technique. Screw placement was uncertain in 48% of Indians due to the presence of aberrant anatomy. CONCLUSIONS: There were significant differences in the metrics of OC-based OCF between Indian and other populations. Because of the smaller occipital squama dimensions in Indians, OC-based OCF techniques may have a higher application rate and could be a viable alternative/salvage option in selected cases. Preoperative CT, including three-dimensional-CT-angiography (to delineate vertebral artery course), is imperative to avoid complications resulting from aberrant bony and vascular anatomy. Our data can serve as a valuable reference guide in placing these screws safely under fluoroscopic guidance. Korean Society of Spine Surgery 2018-04 2018-04-13 /pmc/articles/PMC5913011/ /pubmed/29713401 http://dx.doi.org/10.4184/asj.2018.12.2.214 Text en Copyright © 2018 by Korean Society of Spine Surgery http://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Clinical Study
Bosco, Aju
Venugopal, Prakash
Shetty, Ajoy Prasad
Shanmuganathan, Rajasekaran
Kanna, Rishi Mugesh
Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population
title Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population
title_full Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population
title_fullStr Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population
title_full_unstemmed Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population
title_short Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population
title_sort morphometric evaluation of occipital condyles: defining optimal trajectories and safe screw lengths for occipital condyle-based occipitocervical fixation in indian population
topic Clinical Study
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913011/
https://www.ncbi.nlm.nih.gov/pubmed/29713401
http://dx.doi.org/10.4184/asj.2018.12.2.214
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