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In Vitro Assessment of Serum-Saline Ratios for Fluid Simulator Testing of Highly Modular Spinal Implants With Articulating Surfaces

BACKGROUND: The increasing complexity of articulating spinal implants prohibits the use of serum-supplemented simulator fluid testing because multicomponent interfaces retain residual protein and preclude gravimetric measurement. Our original hypothesis was that simulator testing of a posterior dyna...

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Autores principales: Hallab, Nadim, Khandha, Ashutosh, Malcolmson, George, Timm, JP
Formato: Online Artículo Texto
Lenguaje:English
Publicado: RRY Publications, LLC 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4365664/
https://www.ncbi.nlm.nih.gov/pubmed/25802619
http://dx.doi.org/10.1016/SASJ-2008-0013-RR
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author Hallab, Nadim
Khandha, Ashutosh
Malcolmson, George
Timm, JP
author_facet Hallab, Nadim
Khandha, Ashutosh
Malcolmson, George
Timm, JP
author_sort Hallab, Nadim
collection PubMed
description BACKGROUND: The increasing complexity of articulating spinal implants prohibits the use of serum-supplemented simulator fluid testing because multicomponent interfaces retain residual protein and preclude gravimetric measurement. Our original hypothesis was that simulator testing of a posterior dynamic stabilization implant that has metal-on-metal articulating bearings will not produce dramatically different wear debris when tested using pure saline versus testing in saline supplemented with 20% serum. METHODS: This hypothesis was tested using simulator testing of 12 dynamic stabilization spinal implants, 6 in 100% saline and 6 in 20%-serum saline. Gravimetric and particle analysis were performed after every million cycles up to 10 million cycles, with flexion of 11.3°/extension of 5.6° coupled with axial rotation of ± 4°. RESULTS: The mean gravimetric weight loss was approximately 200 mg over 10 million cycles for the implants tested in 100% saline, while the mean weight loss for those tested in 20%-serum saline was below the method detection limits (< 10 mg over 10 million cycles). For the 100%-saline and 20%-serum simulator fluids, the average particle size over the course of 0 to 10 million cycles remained relatively constant at 0.2 µm-dia (saline) and 3.2 µm-dia (20%-serum saline). Testing in 100% saline generated > 1000-fold more particles, compared to testing in 20% serum-supplemented saline. Energy-dispersive X-ray (EDAX) analyses of particles demonstrated that the 100% saline debris was composed of Co-Cr-P-O (Cr-Co metal oxides), and for the 20%-serum saline debris only bulk metal Co-Cr was detected. CONCLUSION: Our initial hypothesis was not supported. There were significant differences in gravimetric wear, average size, and type of wear debris that were mechanistically attributable to the type of simulator fluid used. The over-protective effect of serum proteins appears to underscore the importance of using both saline and serum when establishing upper and lower bounds of predictive implant debris generation modeling, where saline represents a worst-case scenario and as little as 20% serum masks all weight loss completely in highly modular articulating implants. CLINICAL RELEVANCE: Clinical Relevance = 5 (Oxford Centre for Evidence-based Medicine Levels of Evidence). Study findings are limited to a greater understanding of the science associated with predictive wear testing of articulating spinal implants.
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spelling pubmed-43656642015-03-23 In Vitro Assessment of Serum-Saline Ratios for Fluid Simulator Testing of Highly Modular Spinal Implants With Articulating Surfaces Hallab, Nadim Khandha, Ashutosh Malcolmson, George Timm, JP SAS J Dynamic Stabilization BACKGROUND: The increasing complexity of articulating spinal implants prohibits the use of serum-supplemented simulator fluid testing because multicomponent interfaces retain residual protein and preclude gravimetric measurement. Our original hypothesis was that simulator testing of a posterior dynamic stabilization implant that has metal-on-metal articulating bearings will not produce dramatically different wear debris when tested using pure saline versus testing in saline supplemented with 20% serum. METHODS: This hypothesis was tested using simulator testing of 12 dynamic stabilization spinal implants, 6 in 100% saline and 6 in 20%-serum saline. Gravimetric and particle analysis were performed after every million cycles up to 10 million cycles, with flexion of 11.3°/extension of 5.6° coupled with axial rotation of ± 4°. RESULTS: The mean gravimetric weight loss was approximately 200 mg over 10 million cycles for the implants tested in 100% saline, while the mean weight loss for those tested in 20%-serum saline was below the method detection limits (< 10 mg over 10 million cycles). For the 100%-saline and 20%-serum simulator fluids, the average particle size over the course of 0 to 10 million cycles remained relatively constant at 0.2 µm-dia (saline) and 3.2 µm-dia (20%-serum saline). Testing in 100% saline generated > 1000-fold more particles, compared to testing in 20% serum-supplemented saline. Energy-dispersive X-ray (EDAX) analyses of particles demonstrated that the 100% saline debris was composed of Co-Cr-P-O (Cr-Co metal oxides), and for the 20%-serum saline debris only bulk metal Co-Cr was detected. CONCLUSION: Our initial hypothesis was not supported. There were significant differences in gravimetric wear, average size, and type of wear debris that were mechanistically attributable to the type of simulator fluid used. The over-protective effect of serum proteins appears to underscore the importance of using both saline and serum when establishing upper and lower bounds of predictive implant debris generation modeling, where saline represents a worst-case scenario and as little as 20% serum masks all weight loss completely in highly modular articulating implants. CLINICAL RELEVANCE: Clinical Relevance = 5 (Oxford Centre for Evidence-based Medicine Levels of Evidence). Study findings are limited to a greater understanding of the science associated with predictive wear testing of articulating spinal implants. RRY Publications, LLC 2008-12-01 /pmc/articles/PMC4365664/ /pubmed/25802619 http://dx.doi.org/10.1016/SASJ-2008-0013-RR Text en Copyright SAS - Spine Arthroplasty Society 2008 http://creativecommons.org/licenses/by-nc-nd/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported License, permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Dynamic Stabilization
Hallab, Nadim
Khandha, Ashutosh
Malcolmson, George
Timm, JP
In Vitro Assessment of Serum-Saline Ratios for Fluid Simulator Testing of Highly Modular Spinal Implants With Articulating Surfaces
title In Vitro Assessment of Serum-Saline Ratios for Fluid Simulator Testing of Highly Modular Spinal Implants With Articulating Surfaces
title_full In Vitro Assessment of Serum-Saline Ratios for Fluid Simulator Testing of Highly Modular Spinal Implants With Articulating Surfaces
title_fullStr In Vitro Assessment of Serum-Saline Ratios for Fluid Simulator Testing of Highly Modular Spinal Implants With Articulating Surfaces
title_full_unstemmed In Vitro Assessment of Serum-Saline Ratios for Fluid Simulator Testing of Highly Modular Spinal Implants With Articulating Surfaces
title_short In Vitro Assessment of Serum-Saline Ratios for Fluid Simulator Testing of Highly Modular Spinal Implants With Articulating Surfaces
title_sort in vitro assessment of serum-saline ratios for fluid simulator testing of highly modular spinal implants with articulating surfaces
topic Dynamic Stabilization
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4365664/
https://www.ncbi.nlm.nih.gov/pubmed/25802619
http://dx.doi.org/10.1016/SASJ-2008-0013-RR
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