Multidetector CT in Quantitative Morphometric Assessment of Post-Menopausal Vertebral Fractures in Black Women of Central Africa

Background: Osteoporosis and major Non-Communicable Diseases (NCDs) are identified by WHO as leading cause of death worldwide. Its economic burden is heavy worldwide and in particularly in low income countries. DXA availability is poorly in our country. Spine CT scanner with sagittal reformation images are known for the ease quotation of vertebral fractures by quantitative morphometric system described by Genant et al. (1996). This study aims to determine the rate and the features of vertebral fractures in postmenopausal black women living in Kinshasa/DRC using CT scanner sagittal reconstructions.Patients and methods: 430 consecutives post-menopausal women referred for Thoraco-lumbar CT scanner from June 2011 to June 2016 were enrolled in this study and theirs CT images used to quote vertebrae.Results: 12.89% of a total of 4730 vertebrae were fractured whose more than half (7.82%) of grade 1. The fracture rate is lower than in Caucasian and ASEAN and increase with ageing and duration of menopausis (24.51% in 70 years of age and over).Conclusion: Vertebral fracture global frequency was 12.89%. Vertebral fractures are present in our population and adverse consequences will arises in terms of morbidity and mortality. Lack of infrastucture, health policy and powerty will contributes to boost for a bader pronostics.The method is reproductible and can be used as routine clinical tools in conditions of poor availability of DXA

Undiagnosed vertebral fractures influence quality of life in postmenopausal women with reduced ultrasound parameters.

Osteoporosis, a multifactorial systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue leading to increased bone fragility, is a worldwide public health problem. Vertebral fractures affect approximately 20% of postmenopausal women and are a hallmark of osteoporosis, but they may pass unnoticed, although they may lead to long-term immobility and disability. The aims of the present study were (1) to determine the prevalence and the severity of vertebral fractures in a large cohort of Italian women aged 60 years or older with reduced values of quantitative ultrasound parameters; and (2) to assess whether vertebral fractures and other variables may be associated with health-related quality of life. A total of 2450 women without back pain aged 60 years or older, after the completion of the Quality of Life Questionnaire of the European Foundation for Osteoporosis QUALEFFO, underwent quantitative ultrasound evaluation of the calcaneus; in those with a stiffness t-score of a parts per thousand currency sign -2 (n = 1194), radiographic evaluation of the thoracic and lumbar spine was carried out and then quantitative morphometry was performed by dedicated software (MorphoXpress). The radiographic analysis was carried out on 885 women who presented films of adequate quality. Multivariate regression was used to adjust for confounding variables. Of those who underwent radiographic analysis, 681 had no vertebral fractures, and 204 women (23.1%) had one or more previously undiagnosed vertebral fractures. The prevalence of previously undiagnosed vertebral fractures increased with advancing age with more than 30% of women older than 75 years having at least one fracture. Older age, body mass index, and severe vertebral fractures were independently associated with a worse total QUALEFFO score. We found that approximately one in four women showed evidence of undiagnosed vertebral fractures, and there was a strong age effect trend. Moreover, the severity grade of vertebral fractures, more than the number of fractures, was associated with a worsening of health-related quality of life as assessed by QUALEFFO. These findings confirm the clinical relevance of an early diagnosis of vertebral fractures and seem to support the usefulness of quantitative ultrasound measurements in the stratification of postmenopausal women at increased fracture risk

PhD

dissertationNew methodology was developed to study bone microradiographs on a television image analyzing system, The optimum exposure time for producing microradiographs of 100 micron ground bone sections with sufficient contrast for the quantitative television microscope was determined. The microradiographs were standardized by using a step wedge made from aluminum foil. The microradiographs produced from a bone section (cross-section of lumbar vertebra) ground in several steps from 120 to 70 microns were found to give the same morphometric measurements. With the use of the image editor light pen of the image analyzer (QTM-720) to separate cortical and trabecular bone, complete information of the bone was obtained from the serial cross-sections. The variations of the measurements were detected from one end of the bone to the other leading to the reconstruction of the bone and to a determination of the accuracy of selecting samples for a specific morphometric study. The first lumbar vertebra and the proximal femur from each of 14 beagles were chosen to study changes in morphometric parameters as a function of age and sex. In the cross-sections of the ventral vertebra the maxima of trabecular bone area, percent bone and surface area per volume of tissue were detected at the end potions; these values decreased gradually and had a minimum at the middle part of the main vertebral body. The specific bone surface was more or less uniform within the main vertebral body but dropped abruptly as it reached the end portions where the epiphysis was located. In contrast there were no significant changes in the measurements among sections in the dorsal vertebra; greater trabecular width and higher percent bone were characteristics of this portion. In the cross-sections of the proximal femur the head region had greater trabecular width and higher percent bone than the non-head portion; percent bone was nearly uniform within the head portion but decreased gradually from the proximal end of the non-head portion down into the shaft. The morphometric parameters and dimensions of the bones were presumed to be a function in response to stresses; the variations were observed in beagles of the same age and sex and to a higher degree in the proximal femur than in the vertebra. Bone is rapidly developing in the three month old beagles and could not be compared with the adults. No specific differences in measurements were detected in beagles from 17 months to 11 years, male and female. There was no indication of osteoporosis. Cross-sections of the vertebra and proximal femur showed isotropic orientation of the trabeculae while in the longitudinal sections anisotropic trabeculae were detected in all portions of the vertebra and the non-head portion of the proximal femur. The isotropic structures were preferred for study since the three dimensional measurements could be calculated from a universal k value of 4 over pi whereas in anisotropic structures the k value could not be given directly, since the anisotropy varied from section to section and within different regions of the same section

Viscoelastic finite element analysis of the cervical intervertebral discs in conjunction with a multi-body dynamic model of the human head and neck

This article presents the effects of the frontal and rear-end impact loadings on the cervical spine components by using a multi-body dynamic model of the head and neck, and a viscoelastic finite element (FE) model of the six cervical intervertebral discs. A three-dimensional multi-body model of the human head and neck is used to simulate 15g frontal and 8.5g rear-end impacts. The load history at each intervertebral joint from the predictions of the multi-body model is used as dynamic loading boundary conditions for the FE model of the intervertebral discs. The results from the multi-body model simulations, such as the intervertebral disc loadings in the form of compressive, tensile, and shear forces and moments, and from the FE analysis such as the von Mises stresses in the intervertebral discs are analysed. This study shows that the proposed approach that uses dynamic loading conditions from the multi-body model as input to the FE model has the potential to investigate the kinetics and the kinematics of the cervical spine and its components together with the biomechanical response of the intervertebral discs under the complex dynamic loading history

Mechanical and morphometric characterization of cancellous bone

[EN] Bone fracture is a social health problem of increasing magnitude because of its prevalence in aged population due to osteoporosis. Bone quality is often characterized by bone mineral density (BMD) measured at cancellous bone regions using dual-energy X-ray absorptiometry (DXA). However, BMD alone cannot predict several cases because not only density is important, but also microstructure plays an important role in cancellous bone strength. The mechanical properties can be used as indicators of bone integrity as a function of age, disease or treatment. Therefore, cancellous bone fracture characterization and its relationship to microstructure has not been completely solved in the literature and is relevant to improve fracture prediction. In this thesis, we aim at characterizing cancellous bone morphometry and mechanical behavior. Morphometry is estimated through the analysis of micro-computed tomography (micro-CT) images of vertebral cancellous bone specimens. With regards to the mechanical behavior, we calculate elastic, yield and failure properties at the apparent and tissue levels. To determine them, we followed different approaches: compression tests, finite element models and micro-CT phantoms. We have developed finite element models that reproduce the elastic and failure response of cancellous bone under compression conditions. We modeled failure as a combination of continuum damage mechanics and the element deletion technique. The numerical models permitted to estimate elastic and failure properties. Failure properties were consistent with results reported in the literature. Specifically, our results revealed that yield strain is relatively constant (0.7 %) over a range of apparent densities, while failure strain presents a wider range of variation. A single strain parameter (equivalent strain) was found as an accurate descriptor of cancellous bone compression failure. Image-based numerical models usually need for the action of a technician to segment the images. Therefore, we studied the sensitivity to variations of the segmentation threshold on the morphometry and the elastic properties of vertebral cancellous bone specimens of different bone volume fractions. The apparent modulus is highly sensitive to the segmentation threshold. We report variations between 45 and 120 % for a ± 15 % threshold variation. Other parameters, such as BS/BV, BS/TV, Tb.Sp, Tb.N, Conn.D and fractal dimension were influenced significantly. Digital image correlation (DIC) was applied to images taken during compression testing to analyze displacement fields at failure and characterize them. Some variables were explored to describe failure and a study is done about how DIC parameters influence the strain field obtained. Facet and step sizes have a relevant effect on the failure strain estimation, and an increment of both parameters reduces the strain estimation up to 40 %. Besides, several parameters combination led to correct failure pattern detection, so values reported in the literature should be referred to the parameters used. Furthermore, we explored if cancellous bone microstructure acts (non-speckle/texture approach) as a proper pattern to calculate displacements using DIC technique. As regards relationships between microstructure and mechanics, single and multiple parameter analysis were performed to assess the morphometric variables that control the explanation of mechanical properties variation. Bone volume fraction (BV/TV), bone surface to volume ratio (BS/BV), mean trabecular thickness (Tb.Th) and fractal dimension (D) presented the best linear correlations to the elastic properties, while both the yield and failure strains did not show correlation to any morphometric parameter. The regressions obtained permit to estimate those mechanical properties that describe the state of a specimen.[ES] Las fracturas óseas constituyen un problema social de salud con magnitud creciente por su prevalencia en la población de edad avanzada debido a la osteoporosis. La calidad del hueso suele caracterizarse mediante la estimación de la densidad mineral ósea (DMO) en regiones de hueso trabecular, utilizando absorciometría de rayos X de energía dual (DXA). No obstante, la DMO por si sola no es capaz de predecir numerosos casos de fractura porque no solo importa la pérdida de densidad, sino que la microestructura también tiene un papel principal en la resistencia del hueso. Las propiedades mecánicas del hueso pueden usarse como indicadores de su integridad en función de la edad, enfermedad o tratamiento. Por lo tanto, la caracterización de la fractura de hueso trabecular y su relación con la microestructura no se ha resuelto de forma completa en la literatura y es relevante para mejorar las predicciones de fractura. En esta tesis, nuestro principal objetivo es caracterizar la morfometría y el comportamiento mecánico del hueso trabecular. Estimamos la morfometría a través del análisis de imágenes obtenidas por micro tomografía computerizada (micro-CT) de muestras de hueso trabecular vertebral de cerdo. Respecto al comportamiento mecánico, calculamos propiedades elásticas, de plasticidad y fractura a escala aparente y de tejido. Para determinar esas propiedades, hemos seguido diferentes procedimientos: ensayos a compresión, modelos de elementos finitos y fantomas de calibración micro-CT. Los modelos de elementos finitos desarrollados reproducen la respuesta elástica y de fallo bajo condiciones de compresión en hueso trabecular, modelando el fallo como combinación de mecánica del daño contínuo y la técnica de eliminación de elementos. Los modelos numéricos desarrollados han permitido estimar propiedades elásticas y de fallo. En concreto, las deformaciones de inicio de fallo estimadas son relativamente constantes para las muestras analizadas (0.7 %), mientras que las deformaciones últimas de fallo presentan un rango de variación mayor. Por otro lado, encontramos que la deformación equivalente es el descriptor más preciso del fallo a compresión del hueso trabecular. Normalmente, los modelos numéricos basados en imágenes suelen necesitar la acción de un técnico para segmentar las imágenes. En este sentido, estudiamos la sensibilidad de la morfometría y la estimación de propiedades elásticas ante variaciones en el umbral de segmentación en muestras con distinta fracción en volumen. Hemos obtenido que la rigidez aparente es muy sensible a cambios en el umbral de segmentación, con variaciones entre 45 y 120 % para una variación de ± 15 % del umbral de segmentación. Otros parámetros, como BS/BV, BS/TV, Tb.Sp, Tb.N, Conn.D y la dimensión fractal se ven afectados significativamente. Por otro lado, hemos aplicado la técnica correlación digital por imagen (DIC) para caracterizar campos de desplazamientos en el fallo a compresión del hueso trabecular, a partir del análisis de imágenes tomadas durante el ensayo de las muestras. Además, estudiamos la influencia de algunos parámetros de la técnica DIC en el campo de deformaciones obtenido. También, hemos explorado la aplicación DIC sin el uso de moteado, utilizando como patrón de reconocimiento la propia microestructura trabecular. En relación al estudio de la influencia de la microestructura en la respuesta mecánica, hemos calculado correlaciones de uno y varios parámetros para analizar qué variables morfométricas explican la variación de las propiedades mecánicas. La fracción en volumen de hueso (BV/TV), la relación entre el área y el volumen de hueso (BS/BV), el espesor trabecular medio (Tb.Th) y la dimensión fractal (D) presentan las mejores correlaciones lineales respecto a las propiedades elásticas, mientras que las deformaciones de inicio de plasticidad y fractura no mostraron correlación con ningún parámetro morfométrico.[CA] Les fractures òssies constitueixen un problema social de salut amb magnitud creixent per la seua prevalença en la població d'edat avançada a causa de l'osteoporosi. La qualitat de l'os sol caracteritzar-se mitjançant l'estimació de la densitat mineral òssia (DMO) en regions d'os trabecular, utilitzant absorciometria de raigs X d'energia dual (DXA). No obstant això, la DMO per si sola no és capaç de predir nombrosos casos de fractura perquè no sols importa la pèrdua de densitat, sinó que la microestructura també té un paper principal en la resistència de l'os. Les propietats mecàniques de l'os poden usar-se com a indicadors de la seua integritat en funció de l'edat, malaltia o tractament. Per tant, la caracterització de la fractura d'os trabecular i la seua relació amb la microestructura no s'ha resolt de manera completa en la literatura i és rellevant per a millorar les prediccions de fractura. En aquesta tesi, el nostre principal objectiu és caracteritzar la morfometria i el comportament mecànic de l'os trabecular. Estimem la morfometria a través de l'anàlisi d'imatges obtingudes per micro tomografia automatitzada (micro-CT) de mostres d'os trabecular vertebral de porc. Respecte al comportament mecànic, calculem propietats elàstiques, de plasticitat i fractura a escala aparent i de teixit. Per a determinar aqueixes propietats, hem seguit diferents procediments: assajos a compressió, models d'elements finits i fantomas de calibratge micro-CT. Hem desenvolupat models d'elements finits que reprodueixen la resposta elàstica i de fallada sota condicions de compressió en os trabecular, modelant la fallada com a combinació de mecànica del dany continu i la tècnica d'eliminació d'elements. Els models numèrics desenvolupats han permés estimar propietats elàstiques i de fallada. Les nostres estimacions respecte a propietats de fallada són consistents amb valors reportats en la literatura. En concret, les deformacions d'inici de fallada estimades són relativament constants per a les mostres analitzades (0.7 %), mentre que les deformacions últimes de fallada presenten un rang de variació major. D'altra banda, trobem que la deformació equivalent és el descriptor més precís de la fallada a compressió de l'os trabecular. Els models numèrics basats en imatges solen necessitar l'acció d'un tècnic per a segmentar les imatges. En aquest sentit, estudiem la sensibilitat de la morfometria i l'estimació de propietats elàstiques davant variacions en el llindar de segmentació en mostres amb diferent fracció en volum. Hem obtingut que la rigidesa aparent és molt sensible a canvis en el llindar de segmentació, amb variacions entre 45 i 120 % per a una variació de ± 15 % del llindar de segmentació. Altres paràmetres, com BS/BV, BS/TV, Tb.Sp, Tb.N, Conn.D i la dimensió fractal es veuen afectats significativament. D'altra banda, hem aplicat la tècnica correlació digital per imatge (DIC) per a caracteritzar camps de desplaçaments en la fallada a compressió de l'os trabecular, a partir de l'anàlisi d'imatges preses durant l'assaig de les mostres. A més, estudiem la influència d'alguns paràmetres de la tècnica DIC en el camp de deformacions obtingut. També, hem explorat l'aplicació DIC sense l'ús de clapejat, utilitzant com a patró de reconeixement la pròpia microestructura trabecular. En relació a l'estudi de la influència de la microestructura en la resposta mecànica, hem calculat correlacions d'un i diversos paràmetres per a analitzar quines variables morfomètriques expliquen la variació de les propietats mecàniques. La fracció en volum d'os (BV/TV), la relació entre l'àrea i el volum d'os (BS/BV), la espessor trabecular mitjà (Tb.th) i la dimensió fractal (D) presenten les millors correlacions lineals respecte a les propietats elàstiques, mentre que les deformacions d'inici de plasticitat i fractura no van mostrar correlació amb cap paràmetre morfomètric.Belda González, R. (2020). Mechanical and morphometric characterization of cancellous bone [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149376TESI

Prevalence of “Congenital Lumbar Spinal Stenosis” in Patients with Chronic Low Back Pain in Mombasa

Background: Chronic low back pain is one of the commonest maladies of man. There are multiple causes of chronic low back pain that will include degenerative, inflammatory and mechanical causes. Developmental lumbar spinal stenosis is known to cause symptoms of axial back pain with or without leg pain in the young adult. These symptoms become severer when patients with developmental stenosis acquire degenerative changes as the severity of theca sac and foramina compression increases. We hypothesized that developmental lumbar spinal stenosis is a major predisposing factor for chronic low back pain in adult population.Objective: The purpose of this study was to evaluate the prevalence of developmental lumbar spinal stenosis in a group of individuals suffering from chronic low back pain. This prevalence was compared with another group of asymptomatic individuals (without low back pain). Both Computed Tomography (CT)and Magnetic Resonance Imaging (MRI) images were used for this analysis.Design: This was a prospective, case-control, radiographic study.Subjects: Radiological materials from 118 individuals undergoing MRI scans for chronic low back pain with or without leg pain were analyzed to obtain the AP diameters of the lumbar vertebral body and vertebral canals at L4 and L5 levels. Ninety six patients were enrolled in this study. Abdominal CT scans of 96 patients without back pain were obtained from radiological archives for use as controls.Methods: Using simple statistical methods the association between developmental lumbar spinal stenosis and chronic low back pain was examined.Results: In the study group, 26% of the participants had canal stenosis (AP diameter <12mm) at the distal lumbar canal compared to 8% in the control group; 38% had moderate sized canal (12-14mm) in the study group (31% in control) while only 36% had a normal canal (66% in control group). The differences were found to be statistically significant (95% CI 0.4-1 P=0.0000023). In this study 64% of the patients had a canal diameter below the mean. The presence of a narrow canal is prevalent in these patients with chronic low back pain (Odds ratio 0.3). There was weak correlation between size of the body and size of the canal (Pearson’s r = 0.4).Conclusion: There is significant association between developmental distal lumbar canal stenosis and chronic low back pain in adults

Quantitative Genetic Analysis of Third Metacarpal Morphometry in Baboons (\u3cem\u3ePapio hamadryas\u3c/em\u3e)

Osteoporosis is a very disabling disease in humans, and not until recently with the advent of modern technology has it been researched in a manner beneficial to medical applications. Initially, the use of animals in osteoporosis research served primarily as an avenue for testing and research. Recently the use of nonhuman primates has expanded the research potential for such studies on related individuals more similar to humans. Baboon colonies provide researchers with accessible nonhuman primate populations in which pedigrees can be determined and biomedical studies can be performed. This study is based on 186 hand-wrist radiographs of two baboon subspecies, Papio hamadryas cynocephalus and P.h. anubis, collected at the Southwest Foundation for Biomedical Research in San Antonio, Texas. The records of the baboons from which the radiographs were taken were arranged into pedigrees. The third metacarpal of each radiograph was digitized on a video analysis system using x,y coordinates at 1.0 mm intervals to establish cortical bone area measurements. Subsequent analysis of these measurements established first and second moments of area and radii of gyration. Computer analysis using the program Maxlikh2 , similar to Fischer\u27s Fundamental theorem, determined heritability estimates from the measurements along the parameters of the pedigrees for seven quantitative traits. Heritability is a function of degree of genetic inheritance of a complex trait, in this case radii of gyration of cortical bone. Multivariate analysis using variables mean, sex, age, sex/age interaction, and phenotypic variance and yielded heritability and standard error estimates for the quantitative traits kmax, kmin, area, length, subperiosteal-medullary width, kmax\length, and kmin\length. Quantitative traits are significantly heritable. Cortical bone morphology of baboon third metacarpals may provide a methodology for identifying risk factors associated with developing osteoporosis. The study of bone heritability in primates contributes a new application for osteoporosis research. Studies of bone heritability in baboons could lead to the use of such studies as models for human osteoporosis

Otolith morphometrics and population structure of Pacific sardine (Sardinops sagax) along the west coast of North America

The broad distribution of Pacific sardine (Sardinops sagax) along the Pacif ic coast of North America makes it difficult for fisheries managers to identify regional stocks of this dominant small pelagic species. An investigation of morphometric characteristics of otoliths of Pacific sardine across most of their range revealed regional differences in populations. In a survey of over 2000 otoliths, all ages (with an emphasis on age-1 recruits) were compared. Principal components analysis, multivariate analysis of variance, and a novel method derived from regression and residuals calculations, termed perimeter-weight profiles (PWPs), revealed otolith similarities and differences. The results of the different approaches to statistical comparisons did not always agree. Sardine otoliths from Mexican waters were generally lighter and more lobate than those from U.S. and Canadian populations. Age-1 otoliths from northern California in 2006–07 tended to be heavier and smoother than those from other areas, including year-class cohorts from southern California. Comparisons of age-groups and year-classes of northern California otoliths with the use of the PWP models indicated signif icant trends in year-to-year patterns. In conjunction with other established indices of population structure, otolith PWPs are a useful tool for identifying local and regional stocks of Pacific sardine and may help distinguish populations of other fish species as well