Article Figures & Data
Figures
- Fig. 1
Three-dimensional FEM of ligamentous L3-4 motion segment. A sagittal cross section depicts the contours of Hounsfield units (HU), which were used as a surrogate for BMD.
- Fig. 2
Fernström spheres were virtually implanted to depict 3 levels of subsidence. Sagittal cross-sections of the 3 models are shown: 0 mm of implant subsidence (left), 2 mm of implant subsidence (center), and 4 mm of implant subsidence (right).
- Fig. 3
Graphs depicting first principal strains at various locations along endplate and cortical rim between previously published experimental (Frei et al39) and FEM results.
- Fig. 4
A, Bar graph depicting comparison of angular ROM between FEM versus several previously published values (Heuer et al37, Yamamoto et al40, Mimura et al41, Panjabi et al42, Fujiwara at al43, Schmoelz et al44, Niosi et al45). B, Bar graph showing comparison between FEM and a specific set of experimental data (Niosi et al45), which also includes ranges for the SDs.
- Fig. 5
Effective (von Mises) strain contour plots of L3-4 vertebral bodies at sagittal cut plane for 3 levels of implant subsidence in models implanted with CoCr sphere (top) and models implanted with PEEK implant (bottom).
- Fig. 6
Bar graphs depicting total angular ROM (A) and total FCF (B) for all loading modes and models.
- Fig. 7
Effective (von Mises) strain contour plots of L3-4 vertebral bodies at sagittal or coronal cut plane for all modes of loading and models.
- Fig. 8
Coronal computed tomography image of spherical CoCr interbody device implanted at L5-S1. Vertebral bodies show high signal intensity around the implant at 9 months.
Tables
Component Element type Thickness or cross-sectional area Young modulus (MPa)/Stiffness Parameter Poisson ratio Cortical bone31 Shell 0.4 mm 12,000 0.3 Vertebral endplate32 Shell 0.25 mm 1,000 0.2 Cancellous bone29 , 30 Tet N/A 4,730ρ1.56/1,987ρ1.56/1,357ρ1.56 0.2 Posterior elements33 Tet N/A 3,500 0.25 Annulus fibrosus ground substance34 Hex N/A 1.36 0.45 Annulus fibrosus collagen fibers35 Fabric N/A Stress-strain curve Nucleus pulposus31 Hex N/A K 1,666.7 Incompressible Ligaments36, 37 Spring N/A Hyperelastic N/A Cartilage endplate38 8-Noded hex N/A 24 0.4 Abbervations: Tet, Tetrahedron; Hex, hexahedron; NA, not available.
Axial rotation Extension Lateral bending Flexion 0 mm 80% 70% 50% 10% 2 mm 8% 31% 12% −4% 4 mm −32% −3% −6% −9% Axial rotation Extension Lateral bending 0 mm −16% −41% −48% 2 mm 3% −35% −37% 4 mm 9% 34% 14%
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