| Kinematics of Cervical Total Disc Replacement Adjacent to a Two-Level, Straight vs. Lordotic Fusion (Revision 1). | |
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MedLine Citation:
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PMID: 21629170 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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ABSTRACT: Study design: In-vitro biomechanical study.Objective: To characterize cervical TDR kinematics above 2-level fusion, and to determine the effect of fusion alignment on TDR response.Summary of Background Data: Cervical total disc replacement (TDR) may be a promising alternative for a symptomatic adjacent level after prior multi-level cervical fusion. However, little is known about the TDR kinematics in this setting.Methods: Eight human cadaveric cervical spines (C2-T1, age:59±8.6) were tested intact, after simulated 2-level fusion (C4-C6) in lordotic alignment and then in straight alignment, and after C3-C4 TDR above the C4-C6 fusion in lordotic and straight alignments. Fusion was simulated using an external fixator apparatus, allowing easy adjustment of C4-C6 fusion alignment, and restoration to intact state upon disassembly. Specimens were tested in flexion-extension using hybrid testing protocols.Results: The external fixator device significantly reduced range of motion (ROM) at C4-C6 to 2.0±0.6 degrees, a reduction of 89±3.0% (p<0.05). Removal of the fusion construct restored the motion response of the spinal segments to their intact state. needed to bring the cervical spine to similar C2 motion endpoints significantly increased for the TDR above a two-level fusion compared to TDR alone (p<0.05). Lordotic fusion required significantly greater flexion moment, while straight fusion required significantly greater extension moment (p<0.05).Conclusions: TDR placed adjacent to a two-level fusion is subjected to a more challenging biomechanical environment as compared to a stand-alone TDR. An artificial disc used in such a clinical scenario should be able to accommodate the increased moment loads without causing impingement of its endplates or undue wear during the expected life of the prosthesis. |
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Authors:
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Shelden Martin; Alexander J Ghanayem; Michael N Tzermiadianos; Leonard I Voronov; Robert M Havey; Susan M Renner; Gerard Carandang; Celeste Abjornson; Avinash G Patwardhan |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-5-27 |
Journal Detail:
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Title: Spine Volume: - ISSN: 1528-1159 ISO Abbreviation: - Publication Date: 2011 May |
Date Detail:
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Created Date: 2011-6-1 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7610646 Medline TA: Spine (Phila Pa 1976) Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1 Loyola University Stritch School of Medicine, Maywood, Illinois 2 Edward Hines Jr. VA Hospital, Hines, Illinois 3 Synthes Spine, Paoli, PA, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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