The Mechanical Effect of Commercially Pure Titanium and Polyetheretherketone Rods on Spinal Implants at the Operative and Adjacent Levels

Turner, Joseph L.; Paller, David; Murrell, Charles B.

doi:10.1097/brs.0b013e3181df1b85

Cited by 42 publications

(38 citation statements)

References 18 publications

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“…17 The authors speculate that such flexibility not only allowed the instrumented level to sustain a loading pattern that is more consistent with the intact group, but more importantly, reducing the abnormal compensatory loading at the adjacent levels as seen in the Titanium alloy group. 11,17 Such finding may contribute to the clinical findings of less frequent adjacent segment degeneration after PEEK rod instrumentation. 5 Similar to the observed pattern in the loss of disk height, the Titanium group also demonstrated the least amount of change in the IDP at the instrumented level but with a significant increase in the loss of IDP at the cranial level.…”

Section: Discussionmentioning

confidence: 96%

“…Our results indicated that the PEEK rods construct produced significantly lower bone stress near the screw-bone interface compared with the Titanium alloy rods, which is consistent with other published results. 11,20 It is speculated that the micromovement allowed by the flexible PEEK rods could shift part of the compressive load to the anterior columns and absorb some of the stress through microbending. Our results are in support of the clinical reports of 4% screw breakage 5 and 8% screw looseness rate 8 with PEEK rods implantation compared with 7%-11% hardware failure rate when utilizing the more rigid metallic construct.…”

Section: Discussionmentioning

confidence: 99%

“…The strain data were determined as the loading strain plus unloading strain of each loading cycle. The stress data were calculated by multiplying the elastic modulus (115 GPa for Titanium alloy rods, 3.5 GPa for PEEK rods, and 19.4 GPa for vertebra bone 11,14 ) with the strain value obtained. Custom LabVIEW software (National Instruments, Austin, TX) was used to collect signal data and for analysis.…”

Section: Rod Stress and Bone Stress Near Screw-bone Interfacementioning

confidence: 99%

“…9 Biomechanical studies investigating the adjacent spinal motion and intradiscal pressure (IDP) after Titanium alloy and PEEK rods instrumentation have also failed to identify any significant differences. 10,11 However, it is noted that the biomechanical studies to date were mostly based on single-load test and/or finite element simulations and may contribute to the lack of significant difference between the 2 constructs.…”

mentioning

confidence: 97%

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Biomechanical Analysis Between PEEK and Titanium Screw-rods Spinal Construct Subjected to Fatigue Loading

Chou¹,

Chien²,

Wang

2015

Journal of Spinal Disorders &Amp; Techniques

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Rod Stress and Bone Stress Near Screw-bone Interfacementioning

confidence: 99%

mentioning

confidence: 97%

See 2 more Smart Citations

Biomechanical Analysis Between PEEK and Titanium Screw-rods Spinal Construct Subjected to Fatigue Loading

Chou¹,

Chien²,

Wang

2015

Journal of Spinal Disorders &Amp; Techniques

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“…They suggested distinguishing ''flexible'' devices, which were able to preserve only a minor fraction of the physiological intersegmental range of motion (ROM), from ''dynamic'' devices, which induced a smaller ROM restriction. A biomechanical study by Turner et al [15] using PEEK rods as a kind of fusion technology demonstrated that planar motion showed no differences between the groups instrumented with Ti and PEEK rods.…”

Section: Introductionmentioning

confidence: 99%

Effects of rod stiffness and fusion mass on the adjacent segments after floating mono-segmental fusion: a study using finite element analysis

Jin

Kim²,

Seo³

et al. 2012

Eur Spine J

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Purpose The aims of the present study were to compare the biomechanical effects on the adjacent segments after mono-segmental floating fusion with posterior semi-rigid or rigid stabilization, and to evaluate the effect of the amount of fusion mass on the biomechanical differences. Methods A detailed, nonlinear L1-S1 finite element model had been developed and validated. Then five models were reconstructed by different fixation techniques on the L3-L4 level: rigid fixation with an interbody spacer (Ti ? IS), rigid fixation with a large interbody spacer (Ti ? IS_all), semi-rigid fixation with an interbody spacer (PEEK ? IS), semi-rigid fixation with a large interbody spacer (PEEK ? IS_all), and semi-rigid fixation only (PEEK). Analyses were conducted for the case of erect standing position, flexion, and extension motion. Results At L1-L2 and L2-L3, PEEK ? IS demonstrated less inter-segmental rotation and nucleus pressure increments from the intact model compared with Ti ? IS. The L4-L5 and L5-S1 levels showed slightly higher values with PEEK ? IS, but these differences among the instrumented models were not significant. The motion difference based on the fusion mass at the adjacent levels was at most 3 %. All instrumentation cases generated a 55 % higher facet contact force at the lower adjacent level (L4-L5) compared to that of the intact model during 26°e xtension and the largest increment was detected at the upper adjacent level (L2-L3) in the Ti ? IS. Instrumentation with Ti ? IS markedly increased the stress in the intervertebral disk at the upper adjacent level, while the stress with PEE-K ? IS appeared largest at the lower adjacent level. Conclusions Posterior instrumentation with semi-rigid rods may lower the incidence of disk and facet degeneration in the upper adjacent segment compared to rigid rods. On the other hand, the possibility of facet degeneration will be similar for all instrumentation devices in the lower adjacent segment in the long-term. The stiffness difference between rigid and semi-rigid rods on the changes in the adjacent motion segments was more crucial than amount of fusion mass.

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Pedicle screw‐based posterior dynamic stabilizers for degenerative spine: In vitro biomechanical testing and clinical outcomes

Chamoli

Diwan

Tsafnat

2013

J Biomedical Materials Res

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Dynamic stabilization in a degenerate symptomatic spine may be advantageous compared with conventional fusion procedures, as it helps preserve motion and minimizes redistribution of loads at instrumented and adjacent segments. This article presents a systematic review of biomechanical and clinical evidence available on some of the pedicle screw based posterior dynamic stabilization (PDS) devices. Using Medline, Embase, and Scopus online databases, we identified four pedicle-screw-PDS devices for which both, biomechanical testing and clinical follow-up data are available: Graf artificial ligaments, Isobar TTL, Polyetheretherketone rods, and Dynesys. The current state-of-the-art of pedicle-screw-PDS devices is far from achieving its desired biomechanical efficacy, which has resulted in a weak support for the posited clinical benefits. Although pedicle-screw-PDS devices are useful in salvaging a moderately degenerate functionally suboptimal disc, for severe disc degeneration cases fusion is still the preferred choice. We conclude that a pedicle-screw-PDS device should aim at restoring load sharing amongst spinal elements while preserving the qualitative and quantitative nature of spinal motion, especially minimize posterior shift of the helical axis of motion. More precise and objective assessment techniques need to be standardized for in vivo evaluation of intervertebral motion and load sharing amongst spinal elements across different pedicle-screw-PDS devices.

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The Mechanical Effect of Commercially Pure Titanium and Polyetheretherketone Rods on Spinal Implants at the Operative and Adjacent Levels

Cited by 42 publications

References 18 publications

Biomechanical Analysis Between PEEK and Titanium Screw-rods Spinal Construct Subjected to Fatigue Loading

Biomechanical Analysis Between PEEK and Titanium Screw-rods Spinal Construct Subjected to Fatigue Loading

Effects of rod stiffness and fusion mass on the adjacent segments after floating mono-segmental fusion: a study using finite element analysis

Pedicle screw‐based posterior dynamic stabilizers for degenerative spine: In vitro biomechanical testing and clinical outcomes

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