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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

Normalized left IPT at L4-L5. (IPT = interpedicular travel; DYN = Dynesys; TI = Titanium; FE = flexion-extension; LB = lateral bending; AT = axial torsion; AC = axial compression; ∗ = significant decrease compared to the Intact condition; ◊ = significant decrease compared to the Destabilized condition; † = significant increase compared to the Intact condition.)
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fig6: Normalized left IPT at L4-L5. (IPT = interpedicular travel; DYN = Dynesys; TI = Titanium; FE = flexion-extension; LB = lateral bending; AT = axial torsion; AC = axial compression; ∗ = significant decrease compared to the Intact condition; ◊ = significant decrease compared to the Destabilized condition; † = significant increase compared to the Intact condition.)

Mentions: In FE ID no statistically significant differences were detected between instrumented conditions or between Intact and the Destabilized conditions (Figure 5). DYN, PEEK, and TI conditions showed a significant reduction (69%, 60%, and 65% of Intact, resp.) with respect to both Intact and Destabilized conditions (p ≤ 0.001). In LB no statistically significant differences were detected between instrumented conditions or between Intact and Destabilized conditions. DYN and TI showed significant reductions of 45% and 53% compared to the Intact condition (p ≤ 0.007 and 0.016, resp.), while DYN and TI showed a significant reduction compared to the Destabilized condition (p ≤ 0.001 and 0.012, resp.). Only DYN showed a significant reduction compared to the Destabilized condition in AT (p ≤ 0.041). In AC, the Destabilized condition showed a significantly greater ID compared to all other test conditions (p ≤ 0.042). DYN, PEEK, and TI exhibited reductions of 88%, 80%, and 88% ID compared to the Intact condition (p ≤ 0.001). Again, no significant reductions were found between DYN, PEEK, and TI.


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

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

Normalized left IPT at L4-L5. (IPT = interpedicular travel; DYN = Dynesys; TI = Titanium; FE = flexion-extension; LB = lateral bending; AT = axial torsion; AC = axial compression; ∗ = significant decrease compared to the Intact condition; ◊ = significant decrease compared to the Destabilized condition; † = significant increase compared to the Intact condition.)
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig6: Normalized left IPT at L4-L5. (IPT = interpedicular travel; DYN = Dynesys; TI = Titanium; FE = flexion-extension; LB = lateral bending; AT = axial torsion; AC = axial compression; ∗ = significant decrease compared to the Intact condition; ◊ = significant decrease compared to the Destabilized condition; † = significant increase compared to the Intact condition.)
Mentions: In FE ID no statistically significant differences were detected between instrumented conditions or between Intact and the Destabilized conditions (Figure 5). DYN, PEEK, and TI conditions showed a significant reduction (69%, 60%, and 65% of Intact, resp.) with respect to both Intact and Destabilized conditions (p ≤ 0.001). In LB no statistically significant differences were detected between instrumented conditions or between Intact and Destabilized conditions. DYN and TI showed significant reductions of 45% and 53% compared to the Intact condition (p ≤ 0.007 and 0.016, resp.), while DYN and TI showed a significant reduction compared to the Destabilized condition (p ≤ 0.001 and 0.012, resp.). Only DYN showed a significant reduction compared to the Destabilized condition in AT (p ≤ 0.041). In AC, the Destabilized condition showed a significantly greater ID compared to all other test conditions (p ≤ 0.042). DYN, PEEK, and TI exhibited reductions of 88%, 80%, and 88% ID compared to the Intact condition (p ≤ 0.001). Again, no significant reductions were found between DYN, PEEK, and TI.

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