Regional Variations in Shear Strength and Density of the Human Thoracic Vertebral Endplate and Trabecular Bone

Xavier, Fred; Jauregui, Julio J.; Cornish, Nathan; Jason-Rousseau, Rebecca; Chatterjee, Dipal; Feuer, Gavriel; Hayes, Westley; Kapadia, Bhaveen H.; Carter, John N.; Yoshihara, Hiroyuki; Saha, Subrata

doi:10.14444/4007

Cited by 9 publications

(6 citation statements)

References 18 publications

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“…The range of compressive strengths of the gyroid specimen were between 1.5 and 9.5 MPa and a shear strength of 0.3 and 3.2 MPa. Comparatively, the strength values of cancellous bone in literature were identified in the range of 5.1–6 MPa and a shear strength of 0.5–1.5 MPa 48–50 . The triangle and zig‐zag specimens would require a very low in‐fill density to replicate these features, which may compromise some of the structural properties.…”

Section: Discussionmentioning

confidence: 99%

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An additively manufactured model for preclinical testing of cervical devices

Wahbeh,

Hookasian,

Lama

et al. 2023

JOR Spine

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PurposeComposite models have become commonplace for the assessment of fixation and stability of total joint replacements; however, there are no comparable models for the cervical spine to evaluate fixation. The goal of this study was to create the framework for a tunable non‐homogeneous model of cervical vertebral body by identifying the relationships between strength, in‐fill density, and lattice structure and creating a final architectural framework for specific strengths to be applied to the model.MethodsThe range of material properties for cervical spine were identified from literature. Using additive manufacturing software, rectangular prints with three lattice structures, gyroid, triangle, zig‐zag, and a range of in‐fill densities were 3D‐printed. The compressive and shear strengths for all combinations were calculated in the axial and coronal planes. Eleven unique vertebral regions were selected to represent the distribution of density. Each bone density was converted to strength and subsequently correlated to the lattice structure and in‐fill density with the desired material properties. Finally, a complete cervical vertebra model was 3D‐printed to ensure sufficient print quality.ResultsMaterials testing identified a relationship between in‐fill densities and strength for all lattice structures. The axial compressive strength of the gyroid specimens ranged from 1.5 MPa at 10% infill to 31.3 MPa at 100% infill and the triangle structure ranged from 2.7 MPa at 10% infill to 58.4 MPa at 100% infill. Based on these results, a cervical vertebra model was created utilizing cervical cancellous strength values and the corresponding in‐fill density and lattice structure combination. This model was then printed with 11 different in‐fill densities ranging from 33% gyroid to 84% triangle to ensure successful integration of the non‐homogeneous in‐fill densities and lattice structures.ConclusionsThe findings from this study introduced a framework for using additive manufacturing to create a tunable, customizable biomimetic model of a cervical vertebra.

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Section: Discussionmentioning

confidence: 99%

“…Two studies reported compressive strength specifically in the cervical spine (Table 1 ). 45 , 46 , 47 , 48 , 49 , 50 However, no articles were found that identified the modulus of elasticity or shear strength of cancellous bone in the cervical spine. Therefore, lumbar spine properties were used as a close alternative.…”

Section: Methodsmentioning

confidence: 99%

An additively manufactured model for preclinical testing of cervical devices

Wahbeh,

Hookasian,

Lama

et al. 2023

JOR Spine

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“… 5 Recently, the localized BMD distribution has been widely studied and showed a strong association with bone strength and fracture risk. 24 , 27 , 28 , 29 Moreover, the focal osteoporosis defect observed in routine CT scans, which is a low‐resolution manifestation that correlated with focal microarchitecture changes, 3 has shown a positive association with the osteoporosis. 3 , 6 Nevertheless, most of the previous studies focused on the spatial distribution of the localized bone loss in sub‐regions, while merely quantified the actual structural properties of focal osteoporosis defects in routine CT scans.…”

Section: Discussionmentioning

confidence: 99%

“…However, the sensitivity of the CT‐based bone density to the osteoporotic fracture risk is limited, 26 and it is widely believed that bone quality should also be considered for fracture risk analysis 5 . Recently, the localized BMD distribution has been widely studied and showed a strong association with bone strength and fracture risk 24,27–29 . Moreover, the focal osteoporosis defect observed in routine CT scans, which is a low‐resolution manifestation that correlated with focal microarchitecture changes, 3 has shown a positive association with the osteoporosis 3,6 .…”

Section: Discussionmentioning

confidence: 99%

Focal osteoporosis defect is associated with vertebral compression fracture prevalence in a bone mineral density‐independent manner

Zhuo

et al. 2022

JOR Spine

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Introduction: Focal osteoporosis defect has shown a high association with the bone fragility and osteoporotic fracture prevalence. However, no routine computed tomography (CT)-based vertebral focal osteoporosis defect measurement and its association with vertebral compression fracture (VCF) were discussed yet. This study aimed to develop a routine CT-based measurement method for focal osteoporosis defect quantification, and to assess its association with the VCF prevalence. Materials and Methods: A total of 205 cases who underwent routine CT scanning, were retrospectively reviewed and enrolled into either the VCF or the control group. The focal bone mineral content loss (focal BMC loss), measured as the cumulated demineralization within bone void space, was proposed for focal osteoporosis defect quantification. Its scan-rescan reproducibility and its correlation with trabecular bone mineral density (BMD) and apparent microarchitecture parameters were evaluated.The association between focal BMC loss and the prevalence of VCF was studied by logistic regression. Results:The measurement of focal BMC loss showed high reproducibility (RMSSD = 0.011 mm, LSC = 0.030 mm, ICC = 0.97), and good correlation with focal bone volume fraction (r = 0.79, P < 0.001), trabecular bone separation (r = 0.76, P < 0.001), but poor correlation with trabecular BMD (r = 0.37, P < 0.001). The focal BMC loss was significantly higher in the fracture group than the control (1.03 ± 0.13 vs. 0.93 ± 0.11 mm; P < 0.001), and was associated with prevalent VCF (1.87, 95% CI = 1.31-2.65, P < 0.001) independent of trabecular BMD level.Discussion: As a surrogate measure of focal osteoporosis defect, focal BMC Loss independently associated with the VCF prevalence. It suggests that focal osteoporosis defect is a common manifestation that positively contributed to compression fracture risk and can be quantified with routine CT using focal BMC Loss.

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“…According to anatomical studies of the vertebral endplates from the thoracic spine to the lumbar spine, the center to the anterior portion is the weakest region, while the posterolateral portion is the strongest [13,14]. Therefore, it is important to avoid an excessively large screw insertion angle in the axial direction and to insert the TSD along the axis of the pedicle as much as possible to enable the screw to hold the posterolateral portion of the vertebral endplate.In recent years, there have been increasing reports of the use of the posterior approach and PPSs for minimizing the surgical invasiveness.…”

Section: Discussionmentioning

confidence: 99%

Treatment of Thoracolumbar Spinal Fracture Accompanied by Diffuse Idiopathic Skeletal Hyperostosis Using Transdiscal Screws for Diffuse Idiopathic Skeletal Hyperostosis: Preliminary Results

et al. 2021

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This retrospective case series enrolled 13 patients who underwent posterior fixation with both transdiscal screws for diffuse idiopathic skeletal hyperostosis (TSDs) and pedicle screws (PSs) to treat spinal injury accompanied by diffuse idiopathic skeletal hyperostosis (DISH). Purpose: To describe the usefulness, feasibility, and biomechanics of TSD. Overview of Literature: Vertebral bodies accompanied by DISH generally have lower bone mineral density than normal vertebral bodies because of the stress shielding effect. This phenomenon tends to makes screw fixation challenging. To our knowledge, solutions for this issue have not previously been reported. Methods: Patients were assessed using the data on surgical time, estimated intraoperative blood loss, mean number of stabilized intervertebral segments, number of screws used, perioperative complications, union rate, and the three-level EuroQol five-dimensional questionnaire (EQ5D-3L) score at the final follow-up. The Hounsfield unit (HU) values of the screw trajectory area, and the actual intraoperative screw insertion torque of TSDs and PSs were also analyzed and compared. Results: The surgical time and estimated intraoperative blood loss were 165.9±45.5 minutes and 71.0±53.4 mL, respectively. The mean number of stabilized intervertebral segments was 4.6±1.0. The number of screws used was 4.9±1.3 for TSDs and 3.0±1.4 for PSs. One death occurred after surgery. The union rate and EQ5D-3L scores were 100% and 0.608±0.128, respectively. The HU value and actual intraoperative screw insertion torque of TSDs were significantly better than those of PSs (p<0.001, p=0.033). Conclusions: We were able to achieve stable surgical outcomes using the combination of TSDs and PSs. The HU value and actual intraoperative screw insertion torque were significantly higher for TSDs than for PSs. Based on these results, when treating thoracolumbar spinal fractures accompanied by DISH in elderly populations, the TSD could be a stronger anchor than the PS.

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Regional Variations in Shear Strength and Density of the Human Thoracic Vertebral Endplate and Trabecular Bone

Abstract: Background

Cited by 9 publications

References 18 publications

An additively manufactured model for preclinical testing of cervical devices

An additively manufactured model for preclinical testing of cervical devices

Focal osteoporosis defect is associated with vertebral compression fracture prevalence in a bone mineral density‐independent manner

Treatment of Thoracolumbar Spinal Fracture Accompanied by Diffuse Idiopathic Skeletal Hyperostosis Using Transdiscal Screws for Diffuse Idiopathic Skeletal Hyperostosis: Preliminary Results

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