1,721,020 research outputs found
An in silico bioreactor for simulating laboratory experiments in tissue engineering
No full textThis paper presents a software framework for the computational modeling of tissue engineering experiments, aimed to supplement and extend the empirical techniques currently employed in tissue engineering. The code included a model of cell population dynamics coupled to a finite element model of oxygen diffusion and consumption at the macroscale level, including the scaffold and the culture medium, and at the level of the scaffold microarchitecture. Cells were modeled as discrete entities moving in a continuum space, under the action of adhesion and repulsion forces. Oxygen distribution was calculated with the transient diffusion equation; oxygen consumption by cells was modeled by using the Michaelis-Menten equation. Other phenomena that can be formulated as a differential problem could be added in a straightforward manner to the code, due to the use of a general purpose finite element library. Two scaffold geometries were considered: a fiber scaffold and a scaffold with interconnected spherical pores. Cells were predicted to form clusters and adhere to the scaffold walls. Although the code demonstrated the ability to provide a robust performance, a calibration of the parameters employed in the model, based on specific laboratory experiments, is now required to verify the reliability of the results
Computer-assisted orthopedic surgery
No full textComputer-assisted orthopedic surgery (CAOS) represents one of the most effective means of treatment in clinical orthopedics and, in general, in the treatment of different kinds of musculoskeletal diseases. In fact, the CAOS approach aims at optimizing the surgical process by enhancing the available information with quantitative data, measurements, and estimations during the execution of procedures, so as to enhance the overall surgery-related accuracy, improve the clinical outcomes, and reduce the invasiveness of the surgery itself. In order to achieve this goal, CAOS exploits and integrates a large number of technologies and methodologies, including robotics, tracking devices, clinical images, and modeling. A “biomechanically enhanced” surgery, based on CAOS solutions, may indeed obtain optimal outcomes in a “patient-specific” perspective. This chapter discusses the most relevant details about CAOS systems in terms of general workflow, designs, technologies, methodologies, and applications, with concise hints on the latest advances made by the integration of several concepts borrowed from the musculoskeletal biomechanics within the CAOS workflow
Reply to the letter to the editor entitled: Response to "Comparative analysis of international standards for the fatigue testing of posterior spinal fixation systems".
No full textComparative analysis of international standards for the fatigue testing of posterior spinal fixation systems
No full textEvaluation of different loading conditions prescribed by standards for the fatigue testing of spinal fixators
No full textThe pre-clinical assessment of the long time performances of devices for spinal surgery has peculiar difficulties due to the very complex site of implant: experimental set-ups and procedures prescribed by international standards necessarily represent simplified models of the lumbar tract, thus leading to results that must be carefully evaluated. The purpose of the work is to shed light on the real state of stress arising in the components of a spinal fixator when tested according to different experimental procedures comparing it to the one acting after a virtual implant in a physiological FE model of the lumbar spine
Combined computational study of mechanical behaviour and drug delivery from a porous, hydroxyapatite-based bone graft
No full textThis paper presents a numerical model of a porous, hydroxyapatite-based bone graft also suitable as a
drug delivery device. The graft was positioned in different
sites and with different porosities inside a human femur
model. The structural analyses were carried out to verify the
graft mechanical strength, using the Tsai–Wu criterion, and
the maximum porosity at which static failure does not occur.
A local stress shielding risk was also calculated as the ratio
between the bone stress in the intact condition and the stress
after implantation of the graft. Drug release kinetics was calculated by means of the finite element method. High porosity
grafts were found to fail in all implantation sites. Lower
porosity grafts showed to have adequate strength if implanted
in some positions, while provided insufficient resistance for
other implantation sites. Drug release kinetics was found to
be strongly dependent both on the porosity of the graft and
the bone density near the bone-graft interface
Numerical simulation of mechanical transport behaviour of a porous, hydroxyapatite-based bone graft
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