Rigid and flexible spinal stabilization devices: A biomechanical comparison

Galbusera, Fabio; Bellini, Chiara; Anasetti, Federica; Ciavarro, Cristina; Lovi, Alessio; Brayda-Bruno, Marco

doi:10.1016/j.medengphy.2010.11.018

Cited by 84 publications

(64 citation statements)

References 22 publications

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“…In this paper, the presented classification system (Table 2) was aimed to be more closely related to the clinical aspects of spinal fixation than to the pure stabilization potential. Non-metallic rods, including PEEK, differ from titanium and steel rods in their ability of supporting lower loads, thus transferring higher loads to the anterior column and promoting bony growth [10], as confirmed by the present results. Furthermore, this type of rods may induce a lower stress on the screw-bone interface if compared to metallic rods, thus limiting the risk of screw loosening, despite there is no clinical evidence of this advantage yet [21].…”

Section: Discussionsupporting

confidence: 86%

“…Except for very flexible rods, the stabilization induced by posterior fixation coupled with an interbody cage was not strongly related with the elastic modulus of the rods, coherently with previous data [10,30]. Therefore, if a classification system for the rods is based on the ROM reduction induced by the fixation, as done in the previous paper [30], flexible materials such as PEEK or dynamic systems as the Dynesys would be categorized as rigid.…”

Section: Discussionsupporting

confidence: 80%

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Lumbar interbody fusion: a parametric investigation of a novel cage design with and without posterior instrumentation

2011

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Section: Discussionsupporting

confidence: 86%

Section: Discussionsupporting

confidence: 80%

Lumbar interbody fusion: a parametric investigation of a novel cage design with and without posterior instrumentation

2011

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“…Using a lumbar spinal column finite element model with a paired implant at the L3-L4 level, they found that the stiffness of a posterior implant has only a minor effect on intradiscal pressure (IDP) at the adjacent L2-L3 level despite an increase in intersegmental rotation (ISR) and facet joint forces for axial rotation and extension. A similar analysis was also carried out by Galbusera et al [14]. The effect of stiffness of different rods on the biomechanics of an L2-L5 FE model was studied with the application of a non-fusion stabilization system to the L4-L5.…”

Section: Introductionmentioning

confidence: 86%

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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“…So the unstable degenerative segments are instrumented with the static fixator and the adjacent segments are protected by the dynamic fixator [13]. From a biomechanical viewpoint, mobility of the transition disc can be preserved to some extent and thus the mechanical load can be partially shared by the dynamic fixator [14,15].…”

Section: Introductionmentioning

confidence: 99%

“…Second, which degenerative grade of the transition disc indicates use of a hybrid fixator. To the authors' knowledge, no follow-up study has previously been dedicated to the detailed investigation of these two questions [14,16]. The aim of this study is medium-to long-term retrospective evaluation of clinical and radiographic outcome in the treatment of degenerative lumbar diseases with hybrid posterior fixation.…”

Section: Introductionmentioning

confidence: 99%

Does hybrid fixation prevent junctional disease after posterior fusion for degenerative lumbar disorders? A minimum 5-year follow-up study

et al. 2015

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Purpose Medium-to long-term retrospective evaluation of clinical and radiographic outcome in the treatment of degenerative lumbar diseases with hybrid posterior fixation. Methods Thirty patients were included with the mean age of 47.8 years (range 35 to 60 years). All patients underwent posterior lumbar instrumentation using hybrid fixation for lumbar stenosis with instability (13 cases), degenerative spondylolisthesis Meyerding grade I (6 cases), degenerative disc disease of one or more adjacent levels in six cases and mild lumbar degenerative scoliosis in five patients. Clinical outcomes were evaluated using Oswestry disability index (ODI), Roland and Morris disability questionnaire (RMDQ), and the visual analog scale (VAS) pain scores. All patients were assessed by preoperative, postoperative and follow-up standing plain radiographs and lateral X-rays with flexion and extension. Adjacent disc degeneration was also evaluated by magnetic resonance imaging (MRI) at follow-up.Results At a mean follow-up of 6.1 years, we observed on X-rays and/or MRI 3 cases of adjacent segment disease (10.0 %): two of them (6.6 %) presented symptoms and recurred a new surgery. The last patient (3.3 %) developed asymptomatic retrolisthesis of L3 not requiring revision surgery. The mean preoperative ODI score was 67.6, RMDQ score was 15

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Rigid and flexible spinal stabilization devices: A biomechanical comparison

Cited by 84 publications

References 22 publications

Lumbar interbody fusion: a parametric investigation of a novel cage design with and without posterior instrumentation

Lumbar interbody fusion: a parametric investigation of a novel cage design with and without posterior instrumentation

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

Does hybrid fixation prevent junctional disease after posterior fusion for degenerative lumbar disorders? A minimum 5-year follow-up study

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