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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

IPT and segmented vertebrae. Representative L4-L5 FSU showing displacement of superior vertebra at maximum flexion and extension angles for each treatment. (IPT = interpedicular travel; Destab = Destabilized; DYN = Dynesys; TI = Titanium rod.)
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fig4: IPT and segmented vertebrae. Representative L4-L5 FSU showing displacement of superior vertebra at maximum flexion and extension angles for each treatment. (IPT = interpedicular travel; Destab = Destabilized; DYN = Dynesys; TI = Titanium rod.)

Mentions: Additionally, the head of each pedicle screw was digitized relative to its respective vertebral tracking body and virtually tracked throughout testing (e.g., the heads of the left and right L4 pedicle screws were independently digitized relative to the anterior L4 tracking body). This allowed for the acquisition of IPT and ID measurements. IPT represents the magnitude of the vector describing displacement of adjacent pedicles at the index level between peak loading conditions (Figure 4). This quantifies the magnitude of linear travel of the superior pedicle landmark relative to inferior pedicle. ID on the other hand represents the change in magnitude of interpedicular distance throughout a given ROM and provides information more specific to axial distraction of a device. This describes the change in distance between pedicle landmarks and does not necessarily describe the magnitude of relative translation between them in all situations as does IPT. These metrics have the potential to provide a more complete characterization of PDS constructs and have been previously described in greater detail [32].


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

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

IPT and segmented vertebrae. Representative L4-L5 FSU showing displacement of superior vertebra at maximum flexion and extension angles for each treatment. (IPT = interpedicular travel; Destab = Destabilized; DYN = Dynesys; TI = Titanium rod.)
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig4: IPT and segmented vertebrae. Representative L4-L5 FSU showing displacement of superior vertebra at maximum flexion and extension angles for each treatment. (IPT = interpedicular travel; Destab = Destabilized; DYN = Dynesys; TI = Titanium rod.)
Mentions: Additionally, the head of each pedicle screw was digitized relative to its respective vertebral tracking body and virtually tracked throughout testing (e.g., the heads of the left and right L4 pedicle screws were independently digitized relative to the anterior L4 tracking body). This allowed for the acquisition of IPT and ID measurements. IPT represents the magnitude of the vector describing displacement of adjacent pedicles at the index level between peak loading conditions (Figure 4). This quantifies the magnitude of linear travel of the superior pedicle landmark relative to inferior pedicle. ID on the other hand represents the change in magnitude of interpedicular distance throughout a given ROM and provides information more specific to axial distraction of a device. This describes the change in distance between pedicle landmarks and does not necessarily describe the magnitude of relative translation between them in all situations as does IPT. These metrics have the potential to provide a more complete characterization of PDS constructs and have been previously described in greater detail [32].

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