Artikel
There is no difference between rigid and dynamic plates in a mechanical set up of the cervical spine
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Veröffentlicht: | 21. Mai 2013 |
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Objective: Anterior instabilities of the cervical spine are usually treated using interbody devices, often combined with anterior plates. Especially in trauma cases, rigid plates are thought to be advantageous when compared to dynamic plates. The objective of the study was to investigate, how different types of implants (dynamic and rigid version of QUINTEX, Aesculap, Germany, without and with pedicle screw-rod-fixations) influence range of motion, cage loading and sagittal alignment within CTJ.
Method: 10 human specimens C5-T2 were used and checked within the following conditions: Intact. Following standardised wedge defect within C7: Defect. Following vertebral body resection, replacement C7 and anterior plating ( (5 receiving a rigid, 5 receiving a dynamic plate): ACCF. Following cyclic loading (ACCF cyc). Following additional pedicle-screw-rod-fixation, ACCF + Ped. We analysed for each of these 1. three-dimensional (flexion- extension, left-right lateral bending, left-right axial rotation) flexibility („Range of motion“, ROM) C6-T1, 2. loading of the cage, 3. sagittal alignment C6-T1. ANOVA and least-significance-difference test were used, significance was defined for p<0.05.
Results: ROM: Both plates stabilise the segment, with, however no significant difference between them in any loading condition. Loading of the cage: both plates allowed dramatic peaks in flexion and extension, with again no difference between rigid and dynamic version. Severe kyphosis is produced by the defect, both plates did restore lordosis. For all of these parameters analysed, there was no significant difference between rigid and dynamic plates. The presence of an additional posterior screw-rod fixation significantly reduces flexibility, loading and improves sagittal balance, but there was no difference between both plates in the presence of posterior fixation.
Conclusions: Within this model of an isolated anterior defect within C7, a significant difference between rigid and dynamic version of the plate tested could not be identified. Independently, an additional posterior fixation reduces ROM, cage loading and improves sagittal alignment.