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Developing a multiscale in silico cornea for understanding the role of cell mechanics in corneal pathologies

Pant Anup, Paul Elliot, Vahdati Ali

Biocybernetics and Biomedical Engineering

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2020

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Vol. 40, no. 4

1369--1377

EN

Multiscale in silico modeling of the cell-tissue-organ units is an emerging area of research with the potential to improve our understanding of various disease pathogenesis. Using a multiscale modeling approach, we developed a computational model of the human cornea to investigate how the application of macroscale loads may alter the micro-mechanical environment of the cells. We then utilized the multiscale model to study the effect of physiological and non-physiological mechanical loading conditions such as intraocular pressure (IOP) loading, IOP spike, and eye-poking on the corneal cells. On comparing the results obtained under increased IOP and eye-poking loading, we observed large differences in the averaged principal stress magnitudes in the immediate vicinity of the cell through the thickness of the cornea. On the other hand, our model predicted that under physiological IOP loading, the average principal strain magnitudes in the immediate vicinity of the cell remained almost constant irrespective of the cell location in the stroma. To our knowledge, this is the first study that investigates the effect of mechanical loading on the corneal cells through a multiscale modeling framework. Our computational multiscale cornea model provides a platform to perform virtual experiments and test hypotheses to further our understanding of the potential mechanical cause of multiple diseases in the cornea.

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Biodegradable bone implants in orthopedic applications: a review

Chandra Girish, Pandey Ajay

Biocybernetics and Biomedical Engineering

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2020

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Vol. 40, no. 2

596--610

EN

A biologically - validated biodegradable material must comfortably stay in the physiological environment it is placed in, before finally disappearing over the intended period of time with adequate rates of degradation. The primary objective and utility of such a material is to eliminate the requirement of secondary surgery in applications involving bone implants. In recent decades, biodegradable alloys have exhibited enhanced biocompatibility, and im-proved mechanical and biodegradation properties. This has generated renewed interest in the design of bone implants made up of such materials that can successfully support fractured bone till the culmination of the healing process. However, striking a balance between two seemingly conflicting requirements, namely - sustaining the strength of the implant till the bone acquires the desired strength of its own, and allowing the implant to keep losing strength with its gradual degradation – may be rather complex. To manage this, different healing phases and the associated bone - biodegradable implant interface mechan-obiology needs to be focused upon. An adequate and/or optimal design of the implant is based on mechanical properties, degradation rates of implant and bone-biodegradable implant interface interactivity. This review mainly focuses on bone - biodegradable implant interface with due consideration accorded to the mechanical properties, degradation rates and healing process in a standard duration.

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Material aspects of growth plate modelling using Carter's and Stokes's approaches

Piszczatowski S.

Acta of Bioengineering and Biomechanics

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2011

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Vol. 13, no. 3

3-14

EN

Growth plate, named also as physis, is the anatomical structure responsible for the bone growth. Apart from numerous biological and biochemical factors, biomechanics has also strong influence on its functioning. Loadings acting on the bone element during its development can change (increase or decrease) the velocity of growth. This way mechanobiological processes influence the skeletal development. Several theories try to describe the relationship between loadings acting on the physis and biological processes leading to bone growth and development. Unfortunately, some serious discrepancies exist between them. Additionally, difficulties occur during the modelling of the growth plate activity, which results from the problems in determining material parameters of the particular physis component. The aim of the study was to analyse the influence of material properties of particular parts of the physis on biomechanical conditions of the bone growth. Two concepts, based on the Carter’s and Stokes’s approaches, were applied to estimate the biomechanical stimulation of the bone growth occurring within the physis volume. Results of the numerical simulations show that due to inhomogeneity of the physis structure, the complex 3-D stress state occurs within the growth plate even in the case of uniform axial pressure acting on its surface. The value of the cartilage Poisson’s ratio has a significant influence on the biomechanics of the growth plate activity estimated using both theories. Carter’s model is additionally very sensitive to its dilatational parameter. Both methods lead to non-uniform patterns of mechanical stimulation of the bone growth within the volume of the cartilage. The differences in the stiffness between cartilaginous and bone parts of the growth plate are of fundamental importance for such phenomenon.