scholarly journals Residual strains estimation in the annulus fibrosus through digital image correlation

2021 ◽  
Author(s):  
Gilles Dusfour ◽  
Dominique Ambard ◽  
Patrick Cañadas ◽  
Simon Lefloch
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Annulus Fibrosus ◽  
Ex Vivo ◽  
Image Correlation ◽  
Radial Incision ◽  
Deformation State ◽  
Residual Strains ◽  
The Mean

Up-to-date, back pain is among the most prevalent health issues and generally takes its origins from lesions of the annulus fibrosus (AF). While the AF ex vivo mechanical properties are increasingly well understood, in vivo data are still missing. In particular, very few studies have precisely measured the residual strains within the AF and thus the in vivo deformation state of the AF is still miss-interpreted and miss-evaluated. In this work, we propose an original and robust method for the AF residual strains quantification via digital image correlation technics. Ten pig annulus fibrosus were extracted from adjacent vertebrae followed by a radial incision to release the residual strains. The operations were filmed and then analyzed by a custom digital image correlation software in order to quantify the circumferential, radial and shear residual deformations. Our results show that residual strains are of the same order of magnitude than the in vivo one. The average circumferential strains are in tension on the outer periphery ([3.32; 5.94]%) and in compression on the inner periphery ([−6.4; −1.69]%). The mean radial residual strains are essentially in compression ([−10.4; 2.29]%). Locally, radial and circumferential residual strains can reach really large values up to 40% of compression. The mean shear strains remain very small (−0.04% ± 2.88%). This study also shows that circumferential and radial residual strains evolve linearly along the radius and non-linearly along the angle. We propose a simple model to predict their spatial variations. Our results and methods will allow the quantification of more realistic in vivo strains and stresses within the human intervertebral disc.

The Analysis of Different Stochastic Patterns during Loading in Plastic Area Using DIC Method

2014 ◽  
Vol 611 ◽  
pp. 490-495
Author(s):  
Martin Schrötter ◽  
Martin Hagara ◽  
Matúš Kalina
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Correlation Method ◽  
Mean Value ◽  
Image Correlation ◽  
Black And White ◽  
Unloaded State ◽  
Measured Deformation ◽  
The Mean ◽  
Estimated Error

The aim of this article is to present the influence of stochastic pattern on results accuracy of digital image correlation method in plastic areas. The various types of stochastic patterns were applied on testing specimens which were then tensioned. There was correlated the intensity of black and white color (denoted as grey value) dispersed on a specimen, then the mean value of estimated error for unloaded state as well as state of highest measured deformation and finally the amount of non-correlated facets. Also the maximal deformation of specimens was compared by which the damage of stochastic pattern emerged.

scholarly journals Detection of the Strains Induced in Murine Tibias by Ex Vivo Uniaxial Loading with Different Sensors

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5109
Author(s):  
Emanuele Rizzuto ◽  
Barbara Peruzzi ◽  
Mariagrazia Giudice ◽  
Enrica Urciuoli ◽  
Erika Pittella ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Ex Vivo ◽  
Mean Value ◽  
Uniaxial Loading ◽  
Image Correlation ◽  
Strain Gauges ◽  
Experimental Conditions ◽  
The Mean

In this paper, the characterization of the main techniques and transducers employed to measure local and global strains induced by uniaxial loading of murine tibiae is presented. Micro strain gauges and digital image correlation (DIC) were tested to measure local strains, while a moving coil motor-based length transducer was employed to measure relative global shortening. Local strain is the crucial parameter to be measured when dealing with bone cell mechanotransduction, so we characterized these techniques in the experimental conditions known to activate cell mechanosensing in vivo. The experimental tests were performed using tibia samples excised from twenty-two C57BL/6 mice. To evaluate measurement repeatability we computed the standard deviation of ten repetitive compressions to the mean value. This value was lower than 3% for micro strain gauges, and in the range of 7%–10% for DIC and the length transducer. The coefficient of variation, i.e., the standard deviation to the mean value, was about 35% for strain gauges and the length transducer, and about 40% for DIC. These results provided a comprehensive characterization of three methodologies for local and global bone strain measurement, suggesting a possible field of application on the basis of their advantages and limitations.

scholarly journals Sustained scleral stiffening in rats after a single genipin treatment

2019 ◽  
Vol 16 (159) ◽  
pp. 20190427 ◽  
Author(s):  
Bailey G. Hannon ◽  
Stephen A. Schwaner ◽  
Elizabeth M. Boazak ◽  
Brandon G. Gerberich ◽  
Erin J. Winger ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation ◽  
Brown Norway ◽  
Post Injection ◽  
Functional Studies ◽  
Multiple Treatments ◽  
Lagrange Strain ◽  
Norway Rats

Scleral stiffening has been proposed as a therapy for glaucoma and myopia. Previous in vivo studies have evaluated the efficacy of scleral stiffening after multiple treatments with a natural collagen crosslinker, genipin. However, multiple injections limit clinical translatability. Here, we examined whether scleral stiffening was maintained after four weeks following a single genipin treatment. Eyes from brown Norway rats were treated in vivo with a single 15 mM genipin retrobulbar injection, sham retrobulbar injection, or were left naive. Eyes were enucleated either 1 day or four weeks post-injection and underwent whole globe inflation testing. We assessed first principal Lagrange strain of the posterior sclera using digital image correlation as a proxy for scleral stiffness. Four weeks post-injection, genipin treatment resulted in a 58% reduction in scleral strain as compared to controls ( p = 0.005). We conclude that a single in vivo injection of genipin effectively stiffened rat sclera for at least four weeks which motivates further functional studies and possible clinical translation of genipin-induced scleral stiffening.

scholarly journals Tendon Strain Measurements With Dynamic Ultrasound Images: Evaluation of Digital Image Correlation

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Gregory Okotie ◽  
Sarah Duenwald-Kuehl ◽  
Hirohito Kobayashi ◽  
Mon-Ju Wu ◽  
Ray Vanderby
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Measurement ◽  
Optical Tracking ◽  
Image Correlation ◽  
Image Texture ◽  
Ultrasound Images ◽  
Tendon Strain ◽  
Optical Markers

Strain is an essential metric in tissue mechanics. Strains and strain distributions during functional loads can help identify damaged and pathologic regions as well as quantify functional compromise. Noninvasive strain measurement in vivo is difficult to perform. The goal of this in vitro study is to determine the efficacy of digital image correlation (DIC) methods to measure strain in B-mode ultrasound images. The Achilles tendons of eight male Wistar rats were removed and mechanically cycled between 0 and 1% strain. Three cine video images were captured for each specimen: (1) optical video for manual tracking of optical markers; (2) optical video for DIC tracking of optical surface markers; and (3) ultrasound video for DIC tracking of image texture within the tissue. All three imaging modalities were similarly able to measure tendon strain during cyclic testing. Manual/ImageJ-based strain values linearly correlated with DIC (optical marker)-based strain values for all eight tendons with a slope of 0.970. DIC (optical marker)-based strain values linearly correlated with DIC (ultrasound texture)-based strain values for all eight tendons with a slope of 1.003. Strain measurement using DIC was as accurate as manual image tracking methods, and DIC tracking was equally accurate when tracking ultrasound texture as when tracking optical markers. This study supports the use of DIC to calculate strains directly from the texture present in standard B-mode ultrasound images and supports the use of DIC for in vivo strain measurement using ultrasound images without additional markers, either artificially placed (for optical tracking) or anatomically in view (i.e., bony landmarks and/or muscle-tendon junctions).

scholarly journals Technique for In-Vivo Measurements of Heart Deformation Using Digital Image Correlation

2016 ◽  
Vol 9 (4) ◽  
pp. 1144-1149
Author(s):  
Ronald B. Bucinell ◽  
Matthew T. Adams ◽  
Mcolisi Dlamini ◽  
Leo J. Fleishman
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation

scholarly journals The use of charge-coupled device cameras for characterizing the mean deflected shape of an aerospace panel during broadband excitation

2018 ◽  
Vol 54 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Elias Lopez-Alba ◽  
Christopher M Sebastian ◽  
William JR Christian ◽  
Eann A Patterson
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
High Volume ◽  
Random Excitation ◽  
Frame Rate ◽  
Image Correlation ◽  
Charge Coupled Device ◽  
The Mean ◽  
Standard Frame

In vibration experiments demanding long-duration measurements, traditional point-wise techniques are often employed, despite the availability of high-speed digital image correlation. This is due to the high volume of images generated by the latter technique, which limit acquisition times and lengthen post-processing times. In this experimental investigation, it is demonstrated that standard frame rate charge-coupled device cameras yield results for the mean deflected shape of a reinforced aerospace panel subject to a random broadband excitation between 0 and 800 Hz that are not statistically different to those from high-speed cameras. The images from both types of camera were processed using digital image correlation to generate out-of-plane displacement maps, which were then decomposed using Chebyshev descriptors for ease of comparison and to determine the mean deflected shape. The results indicate that, with appropriate sampling rates and durations, standard frame rate charge-coupled device cameras can be used to study broadband random excitation behavior of structures when mean behavior needs to be characterized over long time scales compared to the excitation wavelengths. This is contrary to accepted procedures, but offers comparable accuracy with substantially reduced computational resources compared to using high-speed cameras, as well as effectively unlimited data acquisition periods, which is useful in condition monitoring, for example.

Sign in / Sign up

Export Citation Format

Share Document