Document Detail


Dynamic stabilization adjacent to single-level fusion: part I. Biomechanical effects on lumbar spinal motion.
MedLine Citation:
PMID:  20683625     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Progression of superior adjacent segment degeneration (PASD) could possibly be avoided by dynamic stabilization of an initially degenerated adjacent segment (AS). The current study evaluates ex vivo the biomechanics of a circumferential fixation connected to posterior dynamic stabilization at the AS. 6 human cadaver spines (L2-S1) were stabilized stepwise through the following conditions for comparison: intact spine (ISP), single-level fixation L5-S1 (SLF), SLF + dynamic AS fixation L4-L5 (DFT), and two-level fixation L4-S1 (TLF). For each condition, the moments required to reach the range of motion (ROM) of the intact whole spine segment under ±10 Nm (WSP10) were compared for all major planes of motion within L2-S1. The ROM at segments L2/3, L3/4, and L4/5 when WSP10 was applied were also compared for each condition. The moments needed to maintain WSP10 increased with each stage of stabilization, from ISP to SLF to DFT to TLF (p < 0.001), in all planes of motion within L2-S1. The ROM increased in the same order at L3/4 (extension, flexion, and lateral bending) and L2/3 (all except right axial rotation, left lateral bending) during WSP10 application with 300 N axial preload (p < 0.005 in ANOVA). At L4/5, while applying WSP10, all planes of motion were affected by stepwise stabilization (p < 0.001): ROM increased from ISP to SLF and decreased from SLF to DFT to TLF (partially p < 0.05). The moments required to reach WSP10 increase dependent on the number of fixated levels and the fixation stiffness of the implants used. Additional fixation shifts motion to the superior segment, according to fixation stiffness. Therefore, dynamic instrumentation cannot be recommended if prevention of hyper-mobility in the adjacent levels is the main target.
Authors:
Patrick Strube; Stephan Tohtz; Eike Hoff; Christian Gross; Carsten Perka; Michael Putzier
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Publication Detail:
Type:  Journal Article     Date:  2010-08-04
Journal Detail:
Title:  European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society     Volume:  19     ISSN:  1432-0932     ISO Abbreviation:  Eur Spine J     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-06     Completed Date:  2011-03-18     Revised Date:  2011-12-21    
Medline Journal Info:
Nlm Unique ID:  9301980     Medline TA:  Eur Spine J     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  2171-80     Citation Subset:  IM    
Affiliation:
Clinic for Orthopaedics, Center for Musculoskeletal Surgery, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
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MeSH Terms
Descriptor/Qualifier:
Aged
Analysis of Variance
Biomechanics / physiology
Bone Screws
Female
Humans
Internal Fixators
Intervertebral Disc / physiology*,  surgery
Lumbar Vertebrae / physiology*,  surgery
Male
Middle Aged
Movement / physiology
Range of Motion, Articular / physiology*
Spinal Fusion / instrumentation

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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