1,721,221 research outputs found
Patient-specific computer modelling of coronary bifurcation stenting: The John Doe programme
No full textJohn Doe, an 81-year-old patient with a significant distal left main (LM) stenosis, was treated using a provisional stenting approach. As part of an European Bifurcation Club (EBC) project, the complete stenting procedure was repeated using computational modelling. First, a tailored three-dimensional (3D) reconstruction of the bifurcation anatomy was created by fusion of multislice computed tomography (CT) imaging and intravascular ultrasound. Second, finite element analysis was employed to deploy and post-dilate the stent virtually within the generated patient-specific anatomical bifurcation model. Finally, blood flow was modelled using computational fluid dynamics. This proof-of-concept study demonstrated the feasibility of such patient-specific simulations for bifurcation stenting and has provided unique insights into the bifurcation anatomy, the technical aspects of LM bifurcation stenting, and the positive impact of adequate post-dilatation on blood flow patterns. Potential clinical applications such as virtual trials and preoperative planning seem feasible but require a thorough clinical validation of the predictive power of these computer simulations
Patient-specific computer modelling of coronary bifurcation stenting: The John Doe programme
Full text linkJohn Doe, an 81-year-old patient with a significant distal left main (LM) stenosis, was treated using a provisional stenting approach. As part of an European Bifurcation Club (EBC) project, the complete stenting procedure was repeated using computational modelling. First, a tailored three-dimensional (3D) reconstruction of the bifurcation anatomy was created by fusion of multislice computed tomography (CT) imaging and intravascular ultrasound. Second, finite element analysis was employed to deploy and post-dilate the stent virtually within the generated patient-specific anatomical bifurcation model. Finally, blood flow was modelled using computational fluid dynamics. This proof-of-concept study demonstrated the feasibility of such patient-specific simulations for bifurcation stenting and has provided unique insights into the bifurcation anatomy, the technical aspects of LM bifurcation stenting, and the positive impact of adequate post-dilatation on blood flow patterns. Potential clinical applications such as virtual trials and preoperative planning seem feasible but require a thorough clinical validation of the predictive power of these computer simulations
Transforming tails into tools : from evolutionary morphology of prehensile tails in syngnathid fishes to exploring bio-inspiration potentials
Full text link
Tailoring of the biomechanics of tissue-regenerative vascular scaffolds
No full textThe lack of long term patency of small diameter synthetic vascular grafts currently available on the market has directed research towards improving the performance of these grafts. Improved radial compliance matching and appropriate tissue ingrowth into the graft structure are main goals for an ideal vascular graft. In addition, the use of biodegradable materials offers the promising prospect of leaving behind a near native vessel with no synthetic material remaining. Tissue ingrowth into grafts alters their mechanics. This, combined with a loss of mechanical integrity over time, in the case of biodegradable scaffolds, brings the need to investigate how these changes play out and how to tailor them for optimal graft healing. This project set out to investigate the mechanics of electrospun Pellethane® 2363-80AE (Dow Chemicals) and DegraPol® (ab medica S.p.A) biostable DegraPol® DP0 and biodegradable DegraPol® DP30 scaffolds during in vivo animal studies. DegraPol® DP30 findings were used to investigate the scaffolds' potential use for vascular grafts by means of a finite element graft model. Porous, electrospun scaffolds were manufactured and implanted into two subcutaneous and one circulatory rat models. All studies consisted of four time points, namely 0, 7, 14 and 28 days. Scaffold morphology was characterised, and tissue ingrowth was quantified by histological analysis of explanted samples. Orthogonal, uni-axial tensile testing measured scaffold mechanical response of in-fibre and cross-fibre deformation. Tissue ingrowth brought about considerable changes in biostable DegraPol® DP0 scaffold mechanics. Tensile testing of degradable DegraPol® DP30 scaffolds in their load bearing circumferential direction showed a balance between a loss in mechanical strength and an increase in strength by tissue ingrowth. This resulted in constant radial compliance of 4.47 ± 0.14%/100 mmHg between 80 and 120 mmHg for the four week period predicted with the numerical models. The finite element model based on DegraPol® DP30 scaffold mechanics for 6 mm grafts showed better, i.e. higher, radial compliance than current grafts used clinically (polyethylene terephthalate and expanded polytetrafluoroethylene grafts). This stability in compliance, coupled with good tissue ingrowth is of scientific importance as it shows that highly aligned, porous electrospun DegraPol® DP30 scaffolds are a viable option for vascular grafting to achieve long term graft patenc
Virtual design of modular 3D printed ankle foot orthoses
Full text linkEnkel-voet-ortheses (EVOs) zijn externe medische hulpmiddelen die het natuurlijk looppatroon van patiënten met neurologische en/of musculoskeletale aandoeningen herstellen. Het ontwerp en de mechanische eigenschappen van het EVO zijn afhankelijk van de behoeftes van de patiënt. Het meest gebruikte productieproces is ‘thermoforming’, waarbij de vaardigheid van de vakman gereflecteerd wordt in de prestaties van de EVO. Dit proces laat niet toe om de mechanische eigenschappen aan te passen en te testen, wat eveneens nadelig is voor de efficiëntie en tijdslijn van het productieproces. Additieve productietechnieken kunnen hiervoor een oplossing bieden, waarbij de vorm en functionaliteit gegarandeerd wordt. Deze doctoraatsthesis onderzoekt het potentieel van 3D geprinte EVOs door hun mechanisch gedrag te analyseren met behulp van simulaties en experimenten. Hiervoor werd een experimentele opstelling ontworpen en patiënt-specifieke eindige elementenmodellen opgesteld, die gevalideerd werden met de experimentele resultaten. Deze modellen en experimenten lieten toe om het mechanisch gedrag van de EVOs beter te begrijpen, en geven relevante informatie voor hun toekomstige ontwikkeling om klinische implementatie te bevorderen
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Morphological characteristics of trochlear dysplasia and their biomechanical impact on the patellofemoral joint
Full text linkKnieschijf-luxaties gaan gepaard met verschillende anatomische afwijkingen ter hoogte van het bot en de weke delen. De belangrijkste uitlokkende factor is een afvlakking van de groeve onderaan het dijbeen, waarin de knieschijf op en neer glijdt tijdens het buigen en strekken van de knie. Vormafwijkingen van deze groeve (trochleodysplasie) komen voor in verschillende variaties, die ingedeeld kunnen worden in 4 klassen. Hoe deze vormvariaties van de groeve de kniefunctie precies beïnvloeden is niet bekend
In het eerste deel van dit doctoraatsonderzoek werd de vorm van een deel van het kniegewricht onderzocht aan de hand van 3D knie-modellen van patiënten. De modellen werden onderworpen aan een analyse op basis van manueel aangeduide referentiepunten en aan een statistische vormanalyse
In het tweede deel werd een nieuwe onderzoeksmethode ontwikkeld om vormafwijkingen van het bot met 3D-printing na te bootsen in kadaverknieën. Er werden kadaver-specifieke prothesen gemaakt, gekenmerkt door verschillende vormafwijkingen. Door deze gemodificeerde kadaverknieën te onderwerpen aan een reeks experimenten kon het effect van de vormafwijkingen onderzocht worden.
De methoden toegepast in dit onderzoek werpen een nieuwe blik op vormvariaties van de groeve en hun invloed op de kniefunctie. Daarenboven kunnen deze vernieuwende methoden ook aangewend worden om andere aspecten van deze en andere aandoeningen te onderzoeken
- …
