Dataset Information

Bone Damage Evolution Around Integrated Metal Screws Using X-Ray Tomography - in situ Pullout and Digital Volume Correlation.

ABSTRACT: Better understanding of the local deformation of the bone network around metallic implants subjected to loading is of importance to assess the mechanical resistance of the bone-implant interface and limit implant failure. In this study, four titanium screws were osseointegrated into rat tibiae for 4 weeks and screw pullout was conducted in situ under x-ray microtomography, recording macroscopic mechanical behavior and full tomographies at multiple load steps before failure. Images were analyzed using Digital Volume Correlation (DVC) to access internal displacement and deformation fields during loading. A repeatable failure pattern was observed, where a ?300-500 ?m-thick envelope of bone detached from the trabecular structure. Fracture initiated close to the screw tip and propagated along the implant surface, at a distance of around 500 ?m. Thus, the fracture pattern appeared to be influenced by the microstructure of the bone formed closely around the threads, which confirmed that the model is relevant for evaluating the effect of pharmacological treatments affecting local bone formation. Moreover, cracks at the tibial plateau were identified by DVC analysis of the tomographic images acquired during loading. Moderate strains were first distributed in the trabecular bone, which localized into higher strains regions with subsequent loading, revealing crack-formation not evident in the tomographic images. The in situ loading methodology followed by DVC is shown to be a powerful tool to study internal deformation and fracture behavior of the newly formed bone close to an implant when subjected to loading. A better understanding of the interface failure may help improve the outcome of surgical implants.

SUBMITTER: Le Cann S

PROVIDER: S-EPMC7419699 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Bone Damage Evolution Around Integrated Metal Screws Using X-Ray Tomography - <i>in situ</i> Pullout and Digital Volume Correlation.

Le Cann Sophie S Tudisco Erika E Tägil Magnus M Hall Stephen A SA Isaksson Hanna H

Frontiers in bioengineering and biotechnology 20200805

Better understanding of the local deformation of the bone network around metallic implants subjected to loading is of importance to assess the mechanical resistance of the bone-implant interface and limit implant failure. In this study, four titanium screws were osseointegrated into rat tibiae for 4 weeks and screw pullout was conducted <i>in situ</i> under x-ray microtomography, recording macroscopic mechanical behavior and full tomographies at multiple load steps before failure. Images were an ...[more]

PMID: 32850760

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Project description:We developed a method to measure the 3-dimensional (3D) strain field in the optic nerve head (ONH) in vivo between two intraocular pressures (IOP). Radial optical coherence tomography (OCT) scans were taken of the ONH of 5 eyes from 5 glaucoma patients before and after IOP-lowering surgery and from 5 eyes from 3 glaucoma suspect patients before and after raising IOP by wearing tight-fitting swimming goggles. Scans taken at higher and lower IOP were compared using a custom digital volume correlation (DVC) algorithm to calculate strains in the anterior lamina cribrosa (ALC), retina, and choroid. Changes in anterior lamina depth (ALD) relative to Bruch's membrane were also analyzed. Average displacement error was estimated to be subpixel and strain errors were smaller than 0.37%. Suturelysis decreased IOP by 9-20 mmHg and decreased compressive anterior-posterior strain Ezz in the ALC by 0.76% (p=0.002,n=5). Goggle-wearing increased IOP by 3-4 mmHg and produced compressive Ezz in the ALC (-0.32%,p=0.001,n=5). Greater IOP decrease was associated with greater ALD change (p=0.047,n=10) and greater strains in the ALC (Ezz:p=0.002,n=10). A deepening of ALD was associated with lower IOP and greater ALC strains (p⩽0.045,n=10). A DVC-based method to measure strains from OCT images caused by IOP changes as small as 2.3 mmHg provides preliminary evidence that ALD is shallower and ALC strains are less compressive at higher IOP and that ALD change is associated with ALC strains. STATEMENT OF SIGNIFICANCE: Glaucoma causes vision loss through progressive damage of the retinal ganglion axons at the lamina cribrosa, a connective tissue structure in the optic nerve head that supports the axons as they pass through the eye wall. It is hypothesized that strains caused by intraocular pressure (IOP) may initiate this damage, but few studies have measured the strain response to pressure of the optic nerve head in patients. We present a method to measure the 3D displacement and strain field in the optic nerve head caused by IOP alteration in glaucoma patients using clinically available images. We used this method to measure strain within the optic nerve head from IOP changes caused by glaucoma surgery and wearing tight-fitting swimming goggles.

Project description:BackgroundBreakthrough imaging technologies may challenge the plant phenotyping bottleneck regarding marker-assisted breeding and genetic mapping. In this context, X-Ray CT (computed tomography) technology can accurately obtain the digital twin of root system architecture (RSA) but computational methods to quantify RSA traits and analyze their changes over time are limited. RSA traits extremely affect agricultural productivity. We develop a spatial-temporal root architectural modeling method based on 4D data from X-ray CT. This novel approach is optimized for high-throughput phenotyping considering the cost-effective time to process the data and the accuracy and robustness of the results. Significant root architectural traits, including root elongation rate, number, length, growth angle, height, diameter, branching map, and volume of axial and lateral roots are extracted from the model based on the digital twin. Our pipeline is divided into two major steps: (i) first, we compute the curve-skeleton based on a constrained Laplacian smoothing algorithm. This skeletal structure determines the registration of the roots over time; (ii) subsequently, the RSA is robustly modeled by a cylindrical fitting to spatially quantify several traits. The experiment was carried out at the Ag Alumni Seed Phenotyping Facility (AAPF) from Purdue University in West Lafayette (IN, USA).ResultsRoots from three samples of tomato plants at two different times and three samples of corn plants at three different times were scanned. Regarding the first step, the PCA analysis of the skeleton is able to accurately and robustly register temporal roots. From the second step, several traits were computed. Two of them were accurately validated using the root digital twin as a ground truth against the cylindrical model: number of branches (RRMSE better than 9%) and volume, reaching a coefficient of determination (R2) of 0.84 and a P < 0.001.ConclusionsThe experimental results support the viability of the developed methodology, being able to provide scalability to a comprehensive analysis in order to perform high throughput root phenotyping.

Dataset Information

Bone Damage Evolution Around Integrated Metal Screws Using X-Ray Tomography - in situ Pullout and Digital Volume Correlation.

Publications

Bone Damage Evolution Around Integrated Metal Screws Using X-Ray Tomography - <i>in situ</i> Pullout and Digital Volume Correlation.

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