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Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies

Rat models are widely used in preclinical studies investigating fracture healing. The interfragmentary movement at a fracture site is critical to the course of healing and therefore demands definition in order to aptly interpret the experimental results. Estimation of this movement requires knowledg...

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Autores principales: Meyers, Nicholaus, Sukopp, Matthias, Jäger, Rudolf, Steiner, Malte, Matthys, Romano, Lapatki, Bernd, Ignatius, Anita, Claes, Lutz
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5409164/
https://www.ncbi.nlm.nih.gov/pubmed/28453556
http://dx.doi.org/10.1371/journal.pone.0176735
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author Meyers, Nicholaus
Sukopp, Matthias
Jäger, Rudolf
Steiner, Malte
Matthys, Romano
Lapatki, Bernd
Ignatius, Anita
Claes, Lutz
author_facet Meyers, Nicholaus
Sukopp, Matthias
Jäger, Rudolf
Steiner, Malte
Matthys, Romano
Lapatki, Bernd
Ignatius, Anita
Claes, Lutz
author_sort Meyers, Nicholaus
collection PubMed
description Rat models are widely used in preclinical studies investigating fracture healing. The interfragmentary movement at a fracture site is critical to the course of healing and therefore demands definition in order to aptly interpret the experimental results. Estimation of this movement requires knowledge of the fixation stiffness and loading. The characteristic loading for the rat femur has been estimated, but the stiffness of fixation used in rat studies has yet to be fully described. This study aimed to determine the 6 degree of freedom stiffness of four commonly used implants, two external fixators (RatExFix and UlmExFix), a locking plate, and a locking intramedullary nail, in all degrees of freedom and estimate the interfragmentary movement under specific physiological loads. The external fixator systems allow the greatest movement. Mounted 45° anterolateral on the femur, the RatExFix allows an average of 0.88 mm of motion in each anatomic direction while the stiffer UlmExFix allows about 0.6 mm of motion. The nail is far stiffer than the other implants investigated while the plate allows movement of an intermediate magnitude. Both the nail and plate demonstrate higher axial than shear stiffness. The relatively large standard deviations in external fixator shear motion imply strong dependence on bone axis alignment across the gap and the precise orientation of the specimen relative to the loading. The smaller standard deviation associated with the nail and plate results from improved alignment and minimization of the influence of rotational positioning of the specimen due to the reduced implant eccentricity relative to the specimen axis. These results show that the interfragmentary movement is complex and varies significantly between fixation devices but establishes a baseline for the evaluation of the results of different studies.
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spelling pubmed-54091642017-05-12 Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies Meyers, Nicholaus Sukopp, Matthias Jäger, Rudolf Steiner, Malte Matthys, Romano Lapatki, Bernd Ignatius, Anita Claes, Lutz PLoS One Research Article Rat models are widely used in preclinical studies investigating fracture healing. The interfragmentary movement at a fracture site is critical to the course of healing and therefore demands definition in order to aptly interpret the experimental results. Estimation of this movement requires knowledge of the fixation stiffness and loading. The characteristic loading for the rat femur has been estimated, but the stiffness of fixation used in rat studies has yet to be fully described. This study aimed to determine the 6 degree of freedom stiffness of four commonly used implants, two external fixators (RatExFix and UlmExFix), a locking plate, and a locking intramedullary nail, in all degrees of freedom and estimate the interfragmentary movement under specific physiological loads. The external fixator systems allow the greatest movement. Mounted 45° anterolateral on the femur, the RatExFix allows an average of 0.88 mm of motion in each anatomic direction while the stiffer UlmExFix allows about 0.6 mm of motion. The nail is far stiffer than the other implants investigated while the plate allows movement of an intermediate magnitude. Both the nail and plate demonstrate higher axial than shear stiffness. The relatively large standard deviations in external fixator shear motion imply strong dependence on bone axis alignment across the gap and the precise orientation of the specimen relative to the loading. The smaller standard deviation associated with the nail and plate results from improved alignment and minimization of the influence of rotational positioning of the specimen due to the reduced implant eccentricity relative to the specimen axis. These results show that the interfragmentary movement is complex and varies significantly between fixation devices but establishes a baseline for the evaluation of the results of different studies. Public Library of Science 2017-04-28 /pmc/articles/PMC5409164/ /pubmed/28453556 http://dx.doi.org/10.1371/journal.pone.0176735 Text en © 2017 Meyers et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Meyers, Nicholaus
Sukopp, Matthias
Jäger, Rudolf
Steiner, Malte
Matthys, Romano
Lapatki, Bernd
Ignatius, Anita
Claes, Lutz
Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies
title Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies
title_full Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies
title_fullStr Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies
title_full_unstemmed Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies
title_short Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies
title_sort characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5409164/
https://www.ncbi.nlm.nih.gov/pubmed/28453556
http://dx.doi.org/10.1371/journal.pone.0176735
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