-
- Heiko Koller, Oliver Meier, Juliane Zenner, Michael Mayer, and Wolfgang Hitzl.
- Werner Wicker Clinic, German Scoliosis Center Bad Wildungen, Im Kreuzfeld 4, 34537 Bad Wildungen, Germany. heiko.koller@t-online.de
- Eur Spine J. 2013 Apr 1; 22 (4): 747758747-58.
IntroductionTo better understand cervical kinematics following cervical disc replacement (CDR), the in vivo behavior of a minimally constrained CDR was assessed.MethodsRadiographic analysis of 19 patients undergoing a 1-level CDR from C4-5 to C6-7 (DISCOVER, Depuy-Spine, USA) was performed. Neutral-lateral and flexion-extension radiographs obtained at preop, postop and late follow-up were analyzed for segmental angle and global angle (GA C2-7). Flexion-extension range of motion was analyzed using validated quantitative motion analysis software (QMA®, Medical Metrics, USA). The FSU motion parameters measured at the index and adjacent levels were angular range of motion (ROM), translation and center of rotation (COR). Translation and COR were normalized to the AP dimension of the inferior endplate of the caudal vertebra. All motion parameters, including COR, were compared with normative reference data.ResultsThe average patient age was 43.5 ± 7.3 years. The mean follow-up was 15.3 ± 7.2 months. C2-7 ROM was 35.9° ± 15.7° at preop and 45.4° ± 13.6° at follow-up (∆p < .01). Based on the QMA at follow-up, angular ROM at the CDR level measured 9.8° ± 5.9° and translation was 10.1 ± 7.8 %. Individuals with higher ROM at the CDR level had increased translation at that level (p < .001, r = 0.97), increased translation and ROM at the supra-adjacent level (p < .001, r = .8; p = .005, r = .6). There was a strong interrelation between angular ROM and translation at the supra-adjacent level (p < .001, r = .9) and caudal-adjacent level (p < .001, r = .9). The location of the COR at the CDR- and supra-adjacent levels was significantly different for the COR-X (p < .001). Notably, the COR-Y at the CDR level was significantly correlated with the extent of CDR-level translation (p = .02, r = .6). Shell angle, which may be influenced by implant size and positioning had no impact on angular ROM but was correlated with COR-X (p = .05, r = -.6) and COR-Y (p = .04, r = -.5).ConclusionThe COR is an important parameter for assessing the ability of non-constrained CDRs to replicate the normal kinematics of a FSU. CDR size and location, both of which can impact shell angle, may influence the amount of translation by affecting the location of the COR. Future research is needed to show how much translation is beneficial concerning clinical outcomes and facet loading.
Notes
Knowledge, pearl, summary or comment to share?You can also include formatting, links, images and footnotes in your notes
- Simple formatting can be added to notes, such as
*italics*
,_underline_
or**bold**
. - Superscript can be denoted by
<sup>text</sup>
and subscript<sub>text</sub>
. - Numbered or bulleted lists can be created using either numbered lines
1. 2. 3.
, hyphens-
or asterisks*
. - Links can be included with:
[my link to pubmed](http://pubmed.com)
- Images can be included with:
![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
- For footnotes use
[^1](This is a footnote.)
inline. - Or use an inline reference
[^1]
to refer to a longer footnote elseweher in the document[^1]: This is a long footnote.
.