Validation efforts and flexibilities of an eight-year-old human juvenile lumbar spine using a three‐dimensional finite element model

Abstract

The objective of this study was to develop a finite element model of the lumbar spinal column of an eight-year-old human spine and compare flexibilities under pure moments, adult, and pediatric loading with different material models. The geometry was extracted from computed tomography scans. The model included the cortical and cancellous bones, growth plates, ligaments, and discs. Adult, adolescent, and pediatric material models were used. Flexion (8 Nm), extension (6 Nm), lateral bending (6 Nm), and axial rotation (4 Nm) moments representing adult loads were applied to the three material models. Pediatric loading (0.5 Nm) was applied under these loadings to the eight-year-old spine using adult and pediatric material models. Flexibilities depended on spinal level, loading mode, and material model. Outputs incorporating the pediatric material model responded with increased flexibilities compared to the adult and adolescent material models, with one exception. This was true for the adult and pediatric loading conditions. While the sagittal and coronal bending responses were not considerably different between the adult and pediatric loadings, axial rotation responses were greater under the adult loading. This model may be used to determine intrinsic responses, such as stresses and strains, for improved characterizations of the juvenile spine behavior.

Smaller Interval Distractions May Reduce Chances of Growth Rod Breakage Without Impeding Desired Spinal Growth: A Finite Element Study

“…The von Mises stresses did not increase much with bending and rotation. The main reason for this is that a child's spine is flexible and moments 10 times smaller than adults are enough to produce an adult-like range of motion in a normal juvenile spine [17]. Therefore, major stresses on the rod resulted from distraction in an upright posture.…”

“…1). The material properties for the juvenile model were taken from the literature (Table 1) [16,17]. The model output was then compared with the only kinematic data (at 0.5 Nm) available in the literature for validation [17][18][19].…”

“…The material properties for the juvenile model were taken from the literature (Table 1) [16,17]. The model output was then compared with the only kinematic data (at 0.5 Nm) available in the literature for validation [17][18][19]. The model includes viscoelastic effects (Table 2) [20,21] and incorporates the HuetereVolkmann principle of growth modulation [22,23].…”

Distraction magnitude and frequency affects the outcome in juvenile idiopathic patients with growth rods: finite element study using a representative scoliotic spine model

“…1 gives a schematic description of this process. The material properties for the spine were taken from the literature, Table [18][19][20][21]. The model also incorporates viscoelastic effects along with Hueter-Volkmann principle of growth modulation [15,16,[22][23][24].…”

“…properties used in the model for bone, ligament, intervertebral disc, and instrumentation[18][19][20][21]. Simulia, Inc., Rhode Island, Providence, USA) was used to construct and analyze the FE models;Table.…”