BACKGROUND: The spatially varying mechanical properties in finite element models of bone are most often derived from bone density data obtained via quantitative computed tomography. The key step is to accurately and efficiently map the density given in voxels to the finite element mesh. METHODS: The density projection is first formulated in least-squares terms and then discretized using a continuous and discontinuous variant of the finite element method. Both discretization variants are compared with the nodal and element approaches known from the literature. FINDINGS: In terms of accuracy in the L2 norm, energy distance and efficiency, the discontinuous zero-order variant appears to be the most advantageous. The proposed variant sufficiently preserves the spectrum of density at the edges, while keeping computational cost low. INTERPRETATION: The continuous finite element method is analogous to the nodal formulation in the literature, while the discontinuous finite element method is analogous to the element formulation. The two variants differ in terms of implementation, computational cost and ability to preserve the density spectrum. These differences cannot be described and measured by known indirect methods from the literature.

• Klíčová slova
• Biomechanics, Bone fracture, Bone stiffness, Computational modeling,
• MeSH
• analýza metodou konečných prvků MeSH
• kosti a kostní tkáň * diagnostické zobrazování   MeSH
• kostní denzita MeSH
• lidé MeSH
• počítačová rentgenová tomografie * metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND AND OBJECTIVE: Capturing the population variability of bone properties is of paramount importance to biomedical engineering. The aim of the present paper is to describe variability and correlations in bone mineral density with a spatial random field inferred from routine computed tomography data. METHODS: Random fields were simulated by transforming pairwise uncorrelated Gaussian random variables into correlated variables through the spectral decomposition of an age-detrended correlation matrix. The validity of the random field model was demonstrated in the spatiotemporal analysis of bone mineral density. The similarity between the computed tomography samples and those generated via random fields was analyzed with the energy distance metric. RESULTS: The random field of bone mineral density was found to be approximately Gaussian/slightly left-skewed/strongly right-skewed at various locations. However, average bone density could be simulated well with the proposed Gaussian random field for which the energy distance, i.e., a measure that quantifies discrepancies between two distribution functions, is convergent with respect to the number of correlation eigenpairs. CONCLUSIONS: The proposed random field model allows the enhancement of computational biomechanical models with variability in bone mineral density, which could increase the usability of the model and provides a step forward in in-silico medicine.

• Klíčová slova
• Finite element method, Karhunen-Loève expansion, Shape registration, Uncertainty quantification,
• MeSH
• kosti a kostní tkáň * MeSH
• kostní denzita * MeSH
• počítačová rentgenová tomografie MeSH
• Publikační typ
• časopisecké články MeSH

A new metric for the quantitative and qualitative evaluation of bone stiffness is introduced. It is based on the spectral decomposition of stiffness matrix computed with finite element method. The here proposed metric is defined as an amplitude rescaled eigenvalues of stiffness matrix. The metric contains unique information on the principal stiffness of bone and reflects both bone shape and material properties. The metric was compared with anthropometrical measures and was tested for sex sensitivity on pelvis bone. Further, the smallest stiffness of pelvis was computed under a certain loading condition and analyzed with respect to sex and direction. The metric complements anthropometrical measures and provides a unique information about the smallest bone stiffness independent from the loading configuration and can be easily computed by state-of-the-art subject specified finite element algorithms.

• MeSH
• algoritmy MeSH
• analýza metodou konečných prvků MeSH
• biofyzika MeSH
• biomechanika * MeSH
• kosti a kostní tkáň * MeSH
• lidé MeSH
• mechanické jevy * MeSH
• spektrální analýza * metody   MeSH
• teoretické modely MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Diffeomorphic shape registration allows for the seamless geometric alignment of shapes. In this study, we demonstrated the use of a registration algorithm to automatically seed anthropological landmarks on the CT images of the pelvis. We found a high correlation between manually and automatically seeded landmarks. The registration algorithm makes it possible to achieve a high degree of automation with the potential to reduce operator errors in the seeding of anthropological landmarks. The results of this study represent a promising step forward in effectively defining the anthropological measures of the human skeleton.

• Klíčová slova
• Anthropometry, CT data, DSP2 method, Geometry segmentation, Non-linear registration,
• MeSH
• algoritmy * MeSH
• anatomická značka * MeSH
• lidé středního věku MeSH
• lidé MeSH
• pánevní kosti anatomie a histologie   diagnostické zobrazování   MeSH
• počítačová rentgenová tomografie * MeSH
• počítačové zpracování obrazu * MeSH
• senioři MeSH
• soudní antropologie metody   MeSH
• určení pohlaví podle kostry metody   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

This study reports changes in costal cartilages that appear at the microscopic level throughout life, especially during the ossification process. The work builds on the results of our previous X-ray study, which confirmed the presence of two sexually dimorphic ossification patterns. This led to questions about the existence of additional sex-specific patterns that relate to the ossification process in costal cartilages. Samples of costal cartilages and adjacent parts of the bones were obtained from the autopsies of 17 corpses. The age range among the cadavers varied greatly, from a newborn baby to 91 years of age. Sections of costal cartilage were routinely processed and stained. Alkaline phosphatase activity was detected using histochemical methods. Collagens type II and X were detected immunohistochemically by monoclonal antibodies. The results of our study show that ossification of costal cartilages can take place in the form of two individual processes, localization and time-separate. Endochondral ossifications in the region of the costochondral zone appear in the first decade, and they correspond to ossifications detected by X-ray in the second decade. The location of sex-specific ossifications is determined by the penetration of cartilage canals into the metaphysial part of the rib. Endochondral intramembranous ossifications in the reserve zone appear after the third decade. These types of ossifications correspond to central globular ossifications detected by X-ray, and they are not sexually dimorphic. They can serve for accurate estimation of age.

• MeSH
• alkalická fosfatasa metabolismus   MeSH
• chondrocyty metabolismus   MeSH
• chrupavka metabolismus   ultrastruktura   MeSH
• dítě MeSH
• dospělí MeSH
• imunohistochemie MeSH
• kojenec MeSH
• kolagen typ II metabolismus   MeSH
• kolagen typ X metabolismus   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mikroskopie * MeSH
• mladiství MeSH
• mladý dospělý MeSH
• novorozenec MeSH
• osteoblasty metabolismus   MeSH
• osteogeneze MeSH
• předškolní dítě MeSH
• proteoglykany metabolismus   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• soudní antropologie MeSH
• stárnutí MeSH
• zvětšování buněk MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• novorozenec MeSH
• předškolní dítě MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alkalická fosfatasa MeSH
• kolagen typ II MeSH
• kolagen typ X MeSH
• proteoglykany MeSH