Article Figures & Data
Figures
- Fig. 1
Posterior (left) and lateral (right) model views showing trans-articular placement of three sacroiliac joint fusion implants in a lumbo-pelvic finite element model.
- Fig. 2
A close-up view of the bone-implant interface. The mating piece is composed of both cancellous and cortical bone that matches the material properties of the adjoining ilium and sacrum. The press fit between the bone and implant was simulated by applying a closing force across the longitudinal slots.
- Fig. 3
Change in range of motion (%) after placement of three sacroiliac joint fusion implants for four directions of loading: A) Flexion, B) Extension, C) Lateral Bending, and D) Axial Rotation. Range of motion was calculated using a hybrid loading protocol in a finite element model.
Tables
Component Element Formulation Young's Modulus(MPa) Poisson's Ratio BonyStructure Vertebral Cortical Bone Isotropic, elastic hexelements 12,000 0.3 Vertebral Cancellous Bone Isotropic, elastic hexelements 100 0.2 Posterior Cortical Bone Isotropic, elastic hexelements 12,000 0.3 Posterior Cancellous Bone Isotropic, elastic hexelements 100 0.2 Pelvic Cortical Bone Isotropic, elastic hexelements 17,000 0.3 Pelvic Cancellous Bone Isotropic, elastic hexelements 10 0.2 Intervertebral Disc Annulus (ground) Neo-Hookean, hexelements C10 = 0.348, D1 = 0.3 Annulus (fiber) Rebar 357-500 0.3 Nucleus Pulposus Incompressible fluid, cavity elements 1 0.499 Ligaments Anterior Longitudinal Tension-only, Trusselements 7.8(<12%),20.0(>12%) 0.3 Posterior Longitudinal Tension-only, Trusselements 10.0(<11%),20.0(>11%) 0.3 LigamentumFlavum Tension-only, Trusselements 15.0(<6.2%),19.5(>6.2%) 0.3 Intertransverse Tension-only, Trusselements 10.0(<18%),58.7(>18%) 0.3 Interspinous Tension-only, Trusselements 10.0(<14%),11.6(>14%) 0.3 Supraspinous Tension-only, Trusselements 8.0(<20%),15.0(>20%) 0.3 Capsular Tension-only, Trusselements 7.5(<25%),32.9(>25%) 0.3 Anterior SI Tension-only, Trusselements 125(<2.5%),175(>5%),325(>10%),316(>15%) 0.3 Inner posteriorSI Tension-only, Trusselements 43(<2.5%), 61(>5%),113(>10%),110(>15%) 0.3 Outer posterior SI Tension-only, Trusselements 150(<2.5%),211(>5%),391(>10%),381(>15%) 0.3 Intraosseus Tension-only, Trusselements 40(<2.5%), 57(>5%),105(>10%),102(>15%) 0.3 Sacrospinous Tension-only, Trusselements 304(<2.5%),428(>5%),792(>10%),771(>15%) 0.3 Sacrotuberous Tension-only, Trusselements 326(<2.5%),458(>5%),848(>10%),826(>15%) 0.3 Joint ApophysealJoints Non-linear Soft contact, GAPPUNIelements - - Sacroiliac Joints Soft Contact with ExponentialBehavior - - - Table 2
Flexion, extension, lateral bending, and axial rotational range of motions for intact and treated sacroiliac (SI) joint. SI joints were treated with three triangular TPS coated implants using a minimally invasive surgical procedure.
Angular Range of Motion (°) Flexion Extension Lateral Bending Axial Rotation Level(s) Intact Treated Intact Treated Intact Treated Intact Treated L1-L2 4.79 4.84 2.04 2.1 13.44 13.46 6.58 6.6 L2-L3 4.87 4.96 2.46 2.55 12.22 12.24 5.82 5.9 L3-L4 5.17 5.34 2.39 2.49 10.08 10.13 5.64 5.79 L4-L5 5.11 5.27 2.74 2.85 9.3 9.34 5.26 5.43 L5-S1 7.11 7.32 3.8 3.94 7.08 7.16 4.79 5.01 SI Joint 1.22 0.53 0.84 0.34 0.72 0.52 1.22 0.57 - Table 3
The change in motion of the cranial segment for two experimental lumbar fusion models and the current finite element sacroiliac study. All studies were completed using motion controlled protocols.
Change in Cranial Segment Range of Motion Site of Fusion Loading Direction Lumbosacral (Ha 1993) Lumbar (Kyaw 2014) Sacroiliac (Current) Flexion 88% 20% 3.0% Extension 56% 20% 3.7% Lateral Bending 26% 21% 1.1% Axial Rotation N/A 127% 4.6%
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