Limits...
In Vitro Comparison of Dynesys, PEEK, and Titanium Constructs in the Lumbar Spine.

Yeager MS, Cook DJ, Cheng BC - Adv Orthop (2015)

Bottom Line: Statistically significant decreases in ROM compared to Intact and Destabilized conditions were detected for the instrumented conditions during flexion extension and lateral bending.Conclusion.The results of this study support previous findings that Dynesys and PEEK constructs behave similarly to a Titanium rod in vitro.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, Allegheny Health Network, Pittsburgh, PA 15212, USA.

ABSTRACT
Introduction. Pedicle based posterior dynamic stabilization systems aim to stabilize the pathologic spine while also allowing sufficient motion to mitigate adjacent level effects. Two flexible constructs that have been proposed to act in such a manner, the Dynesys Dynamic Stabilization System and PEEK rod, have yet to be directly compared in vitro to a rigid Titanium rod. Methods. Human lumbar specimens were tested in flexion extension, lateral bending, and axial torsion to evaluate the following conditions at L4-L5: Intact, Dynesys, PEEK rod, Titanium rod, and Destabilized. Intervertebral range of motion, interpedicular travel, and interpedicular displacement metrics were evaluated from 3rd-cycle data using an optoelectric tracking system. Results. Statistically significant decreases in ROM compared to Intact and Destabilized conditions were detected for the instrumented conditions during flexion extension and lateral bending. AT ROM was significantly less than Destabilized but not the Intact condition. Similar trends were found for interpedicular displacement in all modes of loading; however, interpedicular travel trends were less consistent. More importantly, no metrics under any mode of loading revealed significant differences between Dynesys, PEEK, and Titanium. Conclusion. The results of this study support previous findings that Dynesys and PEEK constructs behave similarly to a Titanium rod in vitro.

No MeSH data available.


Related in: MedlinePlus

Spine with tracking bodies. Tracking bodies are affixed to the anterior column for 3D tracking of vertebral bodies throughout testing. The upper left of the figure shows a virtual representation of the local coordinate frame defined on a tracking body.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4553300&req=5

fig3: Spine with tracking bodies. Tracking bodies are affixed to the anterior column for 3D tracking of vertebral bodies throughout testing. The upper left of the figure shows a virtual representation of the local coordinate frame defined on a tracking body.

Mentions: Kinematic parameters were tracked using an Optotrak Certus motion capture system with a manufacturer stated accuracy of 0.1 mm (Optotrak, Northern Digital Instruments, Waterloo, ON, Canada). Range of motion (ROM) and finite helical axis (FHA) measurements for each intervertebral level were obtained from the anteriorly placed vertebral tracking bodies (Figure 3). ROM was calculated as the range of the Euler angle corresponding to flexion-extension, lateral bending, and axial rotation modes of loading based on vertebral tracking body motion. During axial compression, ROM was defined as the range of translation in the axial direction of each FSU. FHA was also calculated based on the vertebral tracking body motion, based on the method of Reuleaux Woltring et al. [33].


In Vitro Comparison of Dynesys, PEEK, and Titanium Constructs in the Lumbar Spine.

Yeager MS, Cook DJ, Cheng BC - Adv Orthop (2015)

Spine with tracking bodies. Tracking bodies are affixed to the anterior column for 3D tracking of vertebral bodies throughout testing. The upper left of the figure shows a virtual representation of the local coordinate frame defined on a tracking body.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4553300&req=5

fig3: Spine with tracking bodies. Tracking bodies are affixed to the anterior column for 3D tracking of vertebral bodies throughout testing. The upper left of the figure shows a virtual representation of the local coordinate frame defined on a tracking body.
Mentions: Kinematic parameters were tracked using an Optotrak Certus motion capture system with a manufacturer stated accuracy of 0.1 mm (Optotrak, Northern Digital Instruments, Waterloo, ON, Canada). Range of motion (ROM) and finite helical axis (FHA) measurements for each intervertebral level were obtained from the anteriorly placed vertebral tracking bodies (Figure 3). ROM was calculated as the range of the Euler angle corresponding to flexion-extension, lateral bending, and axial rotation modes of loading based on vertebral tracking body motion. During axial compression, ROM was defined as the range of translation in the axial direction of each FSU. FHA was also calculated based on the vertebral tracking body motion, based on the method of Reuleaux Woltring et al. [33].

Bottom Line: Statistically significant decreases in ROM compared to Intact and Destabilized conditions were detected for the instrumented conditions during flexion extension and lateral bending.Conclusion.The results of this study support previous findings that Dynesys and PEEK constructs behave similarly to a Titanium rod in vitro.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, Allegheny Health Network, Pittsburgh, PA 15212, USA.

ABSTRACT
Introduction. Pedicle based posterior dynamic stabilization systems aim to stabilize the pathologic spine while also allowing sufficient motion to mitigate adjacent level effects. Two flexible constructs that have been proposed to act in such a manner, the Dynesys Dynamic Stabilization System and PEEK rod, have yet to be directly compared in vitro to a rigid Titanium rod. Methods. Human lumbar specimens were tested in flexion extension, lateral bending, and axial torsion to evaluate the following conditions at L4-L5: Intact, Dynesys, PEEK rod, Titanium rod, and Destabilized. Intervertebral range of motion, interpedicular travel, and interpedicular displacement metrics were evaluated from 3rd-cycle data using an optoelectric tracking system. Results. Statistically significant decreases in ROM compared to Intact and Destabilized conditions were detected for the instrumented conditions during flexion extension and lateral bending. AT ROM was significantly less than Destabilized but not the Intact condition. Similar trends were found for interpedicular displacement in all modes of loading; however, interpedicular travel trends were less consistent. More importantly, no metrics under any mode of loading revealed significant differences between Dynesys, PEEK, and Titanium. Conclusion. The results of this study support previous findings that Dynesys and PEEK constructs behave similarly to a Titanium rod in vitro.

No MeSH data available.


Related in: MedlinePlus