| Safety evaluation of large external fixation clamps and frames in a magnetic resonance environment. | |
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MedLine Citation:
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PMID: 17034016 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Large orthopedic external fixation clamps and related components were evaluated for force, torque, and heating response when subjected to the strong electromagnetic fields of magnetic-resonance (MR) imaging devices. Forces induced by a 3-Tesla (T) MR scanner were compiled for newly designed nonmagnetic clamps and older clamps that contained ferromagnetic components. Heating trials were performed in a 1.5 and in a 3 T MR scanner with two assembled external fixation frames. Forces of the newly designed clamps were more than a factor 2 lower as the gravitational force on the device whereas, magnetic forces on the older devices showed over 10 times the force induced by earth acceleration of gravity. No torque effects could be found for the newly designed clamps. Temperature measurements at the tips of Schanz screws in the 1.5 T MR scanner showed a rise of 0.7 degrees C for a pelvic frame and of 2.1 degrees C for a diamond knee bridge frame when normalized to a specific absorption rate (SAR) of 2 W/kg. The normalized temperature increases in the 3 T MR scanner were 0.9 degrees C for the pelvic frame and 1.1 degrees C for the knee bridge frame. Large external fixation frames assembled with the newly designed clamps (390 Series Clamps), carbon fiber reinforced rods, and implant quality 316L stainless steel Schanz screws met prevailing force and torque limits when tested in a 3-T field, and demonstrated temperature increase that met IEC-60601 guidelines for extremities. The influence of frame-induced eddy currents on the risk of peripheral nerve stimulation was not investigated. |
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Authors:
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Roger Luechinger; Peter Boesiger; John A Disegi |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Journal of biomedical materials research. Part B, Applied biomaterials Volume: 82 ISSN: 1552-4973 ISO Abbreviation: J. Biomed. Mater. Res. Part B Appl. Biomater. Publication Date: 2007 Jul |
Date Detail:
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Created Date: 2007-06-12 Completed Date: 2007-10-09 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 101234238 Medline TA: J Biomed Mater Res B Appl Biomater Country: United States |
Other Details:
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Languages: eng Pagination: 17-22 Citation Subset: IM |
Copyright Information:
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Copyright 2006 Wiley Periodicals, Inc. |
Affiliation:
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Institute for Biomedical Engineering, University and ETH Zurich, Switzerland. luechinger@biomed.ee.ethz.ch |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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External Fixators* Hot Temperature* Magnetic Resonance Imaging* Magnetics* Materials Testing* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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