Mechanical Properties of Hip Capsule Tissue After a Hip Arthroplasty

Total hip arthroplasty is a surgical procedure that replaces the hip joint by artificial materials. Here, the morphological and mechanical properties of the scar tissues that form around implants composed of either polymer and metal or ceramic are compared to native tissue removed during an initial total hip arthroplasty. Immuno-histological analyses of the samples showed different hierarchical structures of the tissues over three scales: the fiber, the fascicle and the tissue scales. At the tissue scale, micro-tensile tests were performed on millimetric samples and their non-linear elastic responses were identified by either an exponential law or an Ogden third-order constitutive model. At the fiber scale, a patient-specific micro-scale finite element model including the measured morphological parameters and the identified Ogden constitutive models for the fiber and for the matrix composed of a mixture of fibers in ground substance

Microdomain heterogeneity in 3D affects the mechanics of neonatal cardiac myocyte contraction

Abstract Cardiac muscle cells are known to adapt to their physical surroundings, optimizing intracellular organization and contractile function for a given culture environment. A previously developed in vitro model system has shown that the inclusion of discrete microscale domains (or microrods) in three dimensions (3D) can alter long-term growth responses of neonatal ventricular myocytes. The aim of this work was to understand how cellular contact with such a domain affects various mechanical changes involved in cardiac muscle cell remodeling. Myocytes were maintained in 3D gels over 5 days in the presence or absence of 100 − µm-long microrods, and the effect of this local heterogeneity on cell behavior was analyzed via several imaging techniques. Microrod abutment resulted in approximately twofold increases in the maximum displacement of spontaneously beating myocytes, as based on confocal microscopy scans of the gel xy-plane or the myocyte long axis. In addition, microrods caused significant increases in the Electronic supplementary material The online version of this articl

Towards More Predictive, Physiological and Animal-free In Vitro Models: Advances in Cell and Tissue Culture 2020 Conference Proceedings

Experimental systems that faithfully replicate human physiology at cellular, tissue and organ level are crucial to the development of efficacious and safe therapies with high success rates and low cost. The development of such systems is challenging and requires skills, expertise and inputs from a diverse range of experts, such as biologists, physicists, engineers, clinicians and regulatory bodies. Kirkstall Limited, a biotechnology company based in York, UK, organised the annual conference, Advances in Cell and Tissue Culture (ACTC), which brought together people having a variety of expertise and interests, to present and discuss the latest developments in the field of cell and tissue culture and in vitro modelling. The conference has also been influential in engaging animal welfare organisations in the promotion of research, collaborative projects and funding opportunities. This report describes the proceedings of the latest ACTC conference, which was held virtually on 30th September and 1st October 2020, and included sessions on in vitro models in the following areas: advanced skin and respiratory models, neurological disease, cancer research, advanced models including 3-D, fluid flow and co-cultures, diabetes and other age-related disorders, and animal-free research. The roundtable session on the second day was very interactive and drew huge interest, with intriguing discussion taking place among all participants on the theme of replacement of animal models of disease

Multiple scale modeling for crack growth in cortical bone under tension using the eXtended Finite Element Method

International audienceWe present a multiple scale method for modeling multiple crack growth in cortical bone under tension. The four phase composite Haversian microstructure is discretized by a Finite Element Method. The geometrical and mechanical bone parameters obtained by experiments mimic the heterogeneity of bone at the micro scale. The cracks are initiated at the micro scale where a critical elastic-damage strain driven criterion is met and are grown until complete failure in heterogeneous linear elastic media when a critical stress intensity factor criterion is reached. The cracks are modeled by the eXtended Finite Element Method. The simulations provide the global response at the macroscopic level and stress and strain fields at the microscopic level. The model emphasizes the importance of the microstructure on bone failure in assessing the fracture risk

Physical Imaging of fracturing Human Cortical Bone

International audienceIn the present study, we present a procedure associating either the eXtended Finite Element Method (XFEM) or the standard Finite Element Method (FEM) to a Digital Imaging Correlation technique (DIC) called microextensometry (CorrelmanuV) in order to investigate the local fracture toughness of micro cracks in human Haversian cortical bone at the scale of the osteons. The micro cracks are tested in tension and in compression

Fracture strength assessment and aging signs detection in human cortical bone using an X-FEM multiple scale approach.

International audienceWe present a multiple scale approach for modeling multiple crack growth in human cortical bone under tension. The Haversian microstructure, a four phase composite, is discretized by a classical finite element method fed with the morphological and mechanical characteristics, experimentally measured, to mimic human bone heterogeneity at the micro scale. The fracture strength of human bone, exhibiting aging signs, is investigated through tensional percolation simulations in statistical microstructures. The cracks are initiated at the micro scale at locations where a critical elastic-damage strain-driven criterion is met. The cracks, modeled by the eXtended Finite Element Method, are then grown until complete failure when a critical stress intensity factor criterion is attained. The model provides the fracture strength and the global response at the material scale and the stress–strain fields at the microscopic level. The model creates a constitutive law at the material scale and emphasizes the influence of the microstructure on bone failure and fracture risk assessment. These results are validated against experiments

Physical Imaging of Bone Sequential Light Microscopy Observations

National audienceSee http://hal.archives-ouvertes.fr/docs/00/59/27/03/ANNEX/r_OOW53O9P.pd