1,721,051 research outputs found
Numerical simulation of bone remodeling in a prosthetic cotyle-hemipelvis system
No full textAn arthroplasty has the first aim to relieve patient of pain and to restore the correct kinematics of a pathological joint; however it is well known that the insertion of a prosthetic component in a skeletal segment determines a sensible variation of the strain-stress state in bone. It is also well known that bone, in reply to these variations, remodels itself trying to optimize its structural function. This work has the aim to make a personalized analysis of the evolution in time of a prosthetic cotyle-hemipelvis system, in consequence of the action of internal and external bone remodeling. The research done suggests a videodensitometric analysis procedure combined to an analysis of the variation of the periprosthetic bone thickness, followed by a numerical simulation of bone remodeling based on Beaupré et al. theory, completed by relations that link bone remodelling rate to bone density variations and bone density to its structural characteristics, implemented in the Finite Element commercial code Abaqus (Dassault Systèmes)
Repair and remodelling in the shells of the limpet Patella vulgata
No full textLimpets and other molluscs rely on shells to protect them from physical damage, predation, dehydration, etc. If the shell becomes damaged, this may significantly impair its function. In this work, experiments were carried out to investigate the effect of damage on the strength of shells of the common limpet (Patella vulgata) and their ability to repair this damage effectively. Shells were damaged in three ways: (i) low-energy impacts; (ii) abrasion of the outer layer; and (iii) creation of a small hole in the apex of the shell. Shells were left to repair for several time periods (0, 10, 30 and 60 days). The mechanical strength was evaluated by impacting the shells with a weight dropped from a known height. The damage reduced the strength (defined as impact energy to failure) by 50–70% depending on damage type. After 60 days, limpets in all three groups had repaired their shells significantly, bringing their strength to 79–91% of the control value (in each case, samples were statistically indistinguishable from their control counterparts). Measurements of the thickness of the shell at the apex suggest that the main effect of low-energy impact and abrasion is reduction in thickness, which correlates linearly with the impact energy needed for failure. The method of repair is believed to be by the growth of fresh shell material on the inside of the shell, though we could not identify this new material specifically. Even after 60 days, the shells were still statistically thinner than the controls. Consequently, there may be some other strengthening mechanism at work. This work has demonstrated the remarkable ability of limpets to detect the mechanical weakening of their shells caused by relatively subtle forms of damage and to take appropriate action to restore shell strength. © 2018 The Author(s) Published by the Royal Society. All rights reserved
Mock-up in hip arthroplasty pre-operative planning
No full textThe correct estimation of stem boundary conditions in hip arthroplasty cannot be performed simply by subtracting the prosthesis volume from the bone volume: the stem implant path needs to be taken into account. Digital mock-up is a technique commonly applied in the automotive field which can be used for this aim. Given a certain femur, a stem, and an implantation path, the volume of the removed bone stock can be evaluated, as well as the final contact area between the bone and the stem, and, section by section, the residual cortical bone thickness. The technique proved to be useful: if the stem implant path is not considered, the removed bone stock volume can be underestimated up to 6%, while the contact area extension can be overestimated up to 28%. On the whole, a new methodology has been set up and tested, which can be usefully employed to accurately establish stem boundary conditions in the pre-operative planning stage, and in order to perform a reliable structural stress analysis. The methodology implemented here by experienced researchers can be made available to surgeons, setting up an apposite software suite
Bread-derived bioactive porous scaffolds: An innovative and sustainable approach to bone tissue engineering
Full text linkDesign of Additively Manufactured Lattice Structures for Biomedical Applications
Full text linkThe special issue focuses on different features related to the design of additively manufactured lattice structures for biomedical applications. In many cases, the process-structure- property relationship and technical features are discussed from a morphological, mechanical, and functional point of view. In particular, an overview of the Additive Manufacturing processes, software methods, and design criteria, which allow the direct fabrication of 3D porous structures and lattices with tailored properties, are reported. Accordingly, the current special issue aims at providing new insights into the development of advanced devices and illustrates theoretical/experimental approaches used by researchers working in the field
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