Biomechanical assessment of the stabilization capacity of monolithic spinal rods with different flexural stiffness and anchoring arrangement

Facchinello, Yann; Braïlovski, Vladimir; Petit, Yvan; Brummund, Martin; Tremblay, Jaëlle; Mac-Thiong, Jean-Marc

doi:10.1016/j.clinbiomech.2015.09.011

Cited by 16 publications

(27 citation statements)

References 30 publications

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“…At the proximal transition segment rigidity was reduced by about 60% compared to an all-pedicle screw construct. Facchinello et al [ 53 ] and Thawrani et al [ 54 ] reported similar results using proximal hooks showing lower stiffness at the upper instrumented level which applied less force on the anchors. Cahill et al [ 55 ] using computer simulation showed that the use of a transition rod with a proximal decrease in diameter leads to less disc angulation compared to a standard construct.…”

Section: Hybrid Rods or Constructsmentioning

confidence: 73%

Choice of Rods in Surgical Treatment of Adolescent Idiopathic Scoliosis: What Are the Clinical Implications of Biomechanical Properties? – A Review of the Literature

2018

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The surgical treatment of adolescent idiopathic scoliosis (AIS) involves 3-dimensional curve correction with multisegmental pedicle screws attached to contoured bilateral rods. The substantial corrective forces exert a high level of stress on the rods, and the ability of the rod to withstand these forces without undergoing permanent deformation relies on its biomechanical properties. These properties, in turn, are dependent on the material, diameter, and shape of the rod. The surgical treatment of AIS is characterized by the requirement for a special biomechanical profile that may differ substantially from what is needed for adult deformity surgery. This overview summarizes the current knowledge of rod biomechanics in frequently used rod constructs, with a particular focus on translational research between biomechanical studies and clinical applicability in AIS patients.

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Section: Hybrid Rods or Constructsmentioning

confidence: 73%

Choice of Rods in Surgical Treatment of Adolescent Idiopathic Scoliosis: What Are the Clinical Implications of Biomechanical Properties? – A Review of the Literature

2018

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“…Note that the numerical loading condition corresponded to the biomechanical test setup used during the validation experiments. 28 During a first load step, a compressive 400 N FL was applied as recommended in Patwardhan et al 29 and Panjabi. 30 The FL acted in the centre of each vertebral body and was directed towards the centre of the adjacent distal vertebral body 31 Subsequently, an 18° flexion/extension (pure moment) was imposed on the cranial endplate of L1, which is slightly inferior to the range of motion of the porcine lumbar spine under pure moment loading (7.5 N m) 32 and similar to what was applied during in vitro validation experiments.…”

Section: Methodsmentioning

confidence: 99%

“…30 The FL acted in the centre of each vertebral body and was directed towards the centre of the adjacent distal vertebral body 31 Subsequently, an 18° flexion/extension (pure moment) was imposed on the cranial endplate of L1, which is slightly inferior to the range of motion of the porcine lumbar spine under pure moment loading (7.5 N m) 32 and similar to what was applied during in vitro validation experiments. 28 Figure 3 illustrates the boundary and loading conditions used.…”

Section: Methodsmentioning

confidence: 99%

“…All experimental data were previously measured in-house on six porcine lumbar spine models (L1-L6; age: 6-8 months; mass: about 100 kg). 28 In vitro biomechanical experiments were performed under pure moment loading using an MTS MiniBionix (USA) testing apparatus combined with the custommade translation table described in Tremblay et al 18 Spine segments were loaded in flexion and extension motion at 1°/s up to 18°. The speed of 1°/s is coherent with the loading rates used by other authors during quasi-static biomechanical testing of the spine.…”

Section: Model Validationmentioning

confidence: 99%

“…Such a construct could positively affect the mobility transition, as shown in previous experimental studies. 17,28 In addition to reducing the mobility gradient, lowstiffness spinal implants must provide stabilization, where fusion is required. In this respect, functional units L4-L3 to L6-L5 must be monitored closely, as more compliant rods lead to increased IROMs in the instrumented zone.…”

Section: Effect Of Rod Stiffness On Irom Datamentioning

confidence: 99%

See 2 more Smart Citations

Impact of spinal rod stiffness on porcine lumbar biomechanics: Finite element model validation and parametric study

Brummund

Braïlovski

Petit

et al. 2017

Proc Inst Mech Eng H

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A three-dimensional finite element model of the porcine lumbar spine (L1-L6) was used to assess the effect of spinal rod stiffness on lumbar biomechanics. The model was validated through a comparison with in vitro measurements performed on six porcine spine specimens. The validation metrics employed included intervertebral rotations and the nucleus pressure in the first instrumented intervertebral disc. The numerical results obtained suggest that rod stiffness values as low as 0.1 GPa are required to reduce the mobility gradient between the adjacent and instrumented segments and the nucleus pressures across the porcine lumbar spine significantly. Stiffness variations above this threshold value have no significant effect on spine biomechanics. For such low-stiffness rods, intervertebral rotations in the instrumented zone must be monitored closely in order to guarantee solid fusion. Looking ahead, the proposed model will serve to examine the transverse process hooks and variable stiffness rods in order to further smooth the transition between the adjacent and instrumented segments, while preserving the stability of the instrumented zone, which is needed for fusion.

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Ti–Ni Rods with Variable Stiffness for Spine Stabilization: Manufacture and Biomechanical Evaluation

Braïlovski

Facchinello

Brummund

et al. 2016

Shap. Mem. Superelasticity

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Biomechanical assessment of the stabilization capacity of monolithic spinal rods with different flexural stiffness and anchoring arrangement

Cited by 16 publications

References 30 publications

Choice of Rods in Surgical Treatment of Adolescent Idiopathic Scoliosis: What Are the Clinical Implications of Biomechanical Properties? – A Review of the Literature

Choice of Rods in Surgical Treatment of Adolescent Idiopathic Scoliosis: What Are the Clinical Implications of Biomechanical Properties? – A Review of the Literature

Impact of spinal rod stiffness on porcine lumbar biomechanics: Finite element model validation and parametric study

Ti–Ni Rods with Variable Stiffness for Spine Stabilization: Manufacture and Biomechanical Evaluation

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