A biomechanical analog of curve progression and orthotic stabilization in idiopathic scoliosis

Patwardhan, Avinash G.; Bunch, Wilton H.; Meade, Kevin P.; Vanderby, Ray; Knight, Gary W.

doi:10.1016/0021-9290(86)90141-7

Cited by 37 publications

(18 citation statements)

References 15 publications

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“…They found that transverse forces reduced frontal curves but worsened rib hump and axial rotation while posterior forces had the inverse effect. Patwardhan et al [21] modeled the scoliotic spine as a buckling column and studied the effect of brace forces on its stability. They concluded that brace treatment improved the spine stability, that the forces should be applied at and below the apex of curves and that the gain in stability increased with the correction of the frontal curves.…”

Section: Introductionmentioning

confidence: 99%

Virtual prototyping of a brace design for the correction of scoliotic deformities

2007

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Based on a three-dimensional patient-specific finite element model of the spine, rib cage, pelvis and abdomen, a parametric model of a thoraco-lumbo-sacral orthosis (TLSO) was built. Its geometry is custom-fit to the patient. The rigid shell, pads and openings are all represented. The interaction between the trunk and the brace is modeled by a point-to-surface contact interface. During the nonlinear simulation process, the brace is opened, positioned on the patient and strap tension is applied. A TLSO similar to Boston brace system was built for a right-thoracic scoliotic patient. The influences of the trochanter pad and strap tension on the 3-D geometrical corrections and on the forces generated by the brace were evaluated. The role of the trochanter pad as a lever arm is confirmed by the model. The brace induces a reduction of the lordosis and pelvic tilt. The reduction of the frontal curvature is about 20% for a strap tension of 60 N. Axial rotation does not significantly change and rib hump is worsened. By using an explicit brace model and a contact interface, a more realistic simulation of orthotic treatment of scoliosis can be achieved. The stabilization of the brace on the patient can be represented and less restrictive boundary conditions can be applied. This model could be used to study the effect of design parameters on the brace efficiency.

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Section: Introductionmentioning

confidence: 99%

Virtual prototyping of a brace design for the correction of scoliotic deformities

2007

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“…This displacement y 1 (x) is modelled [16] by the differential equation (4) 1 + Py 1 = Q − Py 0 , where EI is the flexural rigidity of the beam-column, P the axial load and Q the transverse load. As it is well known in the elasticity theory, this shearing force Q is related with the third derivative of the displacement (see, for instance, [11]).…”

Section: Continuous Model For the Human Spine Deformationmentioning

confidence: 99%

“…The mechanical properties of the human spine have been studied by several authors (see [16] and references therein) by a continuous beam model. Of course this type of models cannot describe certain local features of the spine.…”

Section: Continuous Model For the Human Spine Deformationmentioning

confidence: 99%

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Fully nonlinear fourth-order equations with functional boundary conditions

Cabada

Minhós

2008

Journal of Mathematical Analysis and Applications

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The aim of this paper consists in to give sufficient conditions to ensure the existence and location of the solutions of a nonlinear fully fourth-order equation with functional boundary conditions. The arguments make use of the upper and lower solutions method, a φ-Laplacian operator and a fixed point theorem. An application of the beam theory to a nonlinear continuous model of the human spine allows to estimate its deformation under some loading forces.

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“…Andriacchi et al [1] simulated the Milwaukee brace and Périé et al [25,27] the Boston brace using such approach. Patwardhan et al [21], Wynarsky et al [37], and Gignac et al [8] studied the optimal forces that a brace should exert but the optimization processes did not include many brace design parameters, such as the strap tension, the rigid shell geometry, or the shape of the pads. More recently, Périé et al [26] introduced an explicit FEM of the brace.…”

Section: Introductionmentioning

confidence: 99%

Biomechanical modeling of brace treatment of scoliosis: effects of gravitational loads

Clin

Aubin

Parent

2011

Med Biol Eng Comput

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The biomechanics of bracing in adolescent idiopathic scoliosis is still not fully understood. Finite element models (FEM) have been used but the gravity forces were not included and the production of spinal stresses not evaluated. An improved FEM to simulate brace treatment was thus developed. The 3D geometry of the spine, rib cage, pelvis, and of the trunk external surface of five scoliotic patients was acquired using a multi-view X-ray technique and surface topography. A FEM of the patient's trunk including gravity forces was created. Custom-fit braces were modeled and their installation simulated. Immediate geometrical corrections and pressures were computed and validated. The resulting compressive loads on the vertebral endplates were quantified. The influence of the strap tension, spine stiffness, and of the gravity forces was evaluated. Results showed that the brace biomechanical action was importantly to prevent the scoliotic spine from bending under the gravity forces. The immediate correction depended on the strap tension and spine stiffness. The distribution and amplitude of computed pressures were similar to those measured with the real braces. After the brace installation, the coronal asymmetrical compressive loading on the vertebral endplates was significantly reduced. In conclusion, the model developed presents improvements over previous models and could be used to better understand and optimize brace treatment.

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A biomechanical analog of curve progression and orthotic stabilization in idiopathic scoliosis

Cited by 37 publications

References 15 publications

Virtual prototyping of a brace design for the correction of scoliotic deformities

Virtual prototyping of a brace design for the correction of scoliotic deformities

Fully nonlinear fourth-order equations with functional boundary conditions

Biomechanical modeling of brace treatment of scoliosis: effects of gravitational loads

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