| 1. |
- Fahlgren, Anna, et al.
(författare)
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Direct ex vivo measurement of the fluid permeability of loose scar tissue
- 2012
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Ingår i: Acta of Bioengineering and Biomechanics. - Wroclaw, Poland : Wroclaw University of Technology. - 1509-409X. ; 14:2, s. 47-51
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Tidskriftsartikel (refereegranskat)abstract
- Fluid flow is important in many biomechanical models, but there is a lack of experimental data that quantifies soft tissue permeability. We measured the tissue permeability in fibrous soft tissue, using a novel technique to obtain specimens by allowing soft tissue to grow into coralline hydroxyapatite scaffoldings implanted between the abdominal muscle layers of rats.
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| 2. |
- Hazay, Máté, et al.
(författare)
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Engineering optimization of decompressive craniectomy based on finite element simulations
- 2020
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Ingår i: Acta of bioengineering and biomechanics. - : Wroclaw University of Technology. - 1509-409X .- 1509-409X. ; 22:4, s. 109-122
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The optimal execution of decompressive craniectomy in terms of the size and location of the skull opening is not straightforward. Our main goals are twofold: (1) constructing a design optimization method which can be applied to determine optimal skull opening for individual patient-specific cases and (2) performing a large-scale parametric optimization study to give some guidance in general about the optimal skull opening in case of oedematous brain tissue.Methods: A large number of virtual experiments performed by finite element simulations were applied to determine tendencies of tissue behaviour during surgery. The multiobjective optimization is performed by Goal Programming and Physical Programming methods.Results: Our results show that the postoperative pressure has an approximately linear dependence on the preoperative pressure and the skull opening area, while the damaged brain volume could have a more complex nonlinear dependence on the input data. Based on the averaged results of the parametric optimization study, the optimal skull opening has been determined in the function of the preoperative pressure and the relative importance of the pressure reduction. These results show that the optimal size of the unilateral skull opening is usually between 130-180 cm² and these openings are more beneficial than the currently analysed bifrontal openings.Conclusions: The optimal skull opening is patient-specific and depends on several input data. The presented methodology can be applied to optimize surgery based on these input parameters for different injury types. Based on the results of large-scale parametric study generally applicable approximate results have been provided.
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| 3. |
- Kharmanda, Ghias, et al.
(författare)
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Integration of reliability analysis into mini-plate fixation strategy used in human mandible fractures : Convalescence and healing periods
- 2017
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Ingår i: Acta of Bioengineering and Biomechanics. - 1509-409X. ; 19:4, s. 13-23
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The objective was to assess the reliability level of mini-plate fixation used in fracture mandibles in order to evaluate the structure stability in both convalescence and healing periods. Methods: In the convalescence period, the failure scenario is measured by the relative displacement between two fracture surfaces which should not exceed an acceptable value in order to obtain a good stability for rapid bone healing and to limit any trauma. However, in the healing period, it is the objective to obtain an acceptable rigidity. Hereby, the failure scenario is measured by the von Mises stresses being as indicator of mandible fractures. Results: During the surgery operation, some muscles can be cut or harmed and cannot operate at its maximum capability. Thus, there is a strong motivation to introduce the loading uncertainties in order to obtain reliable designs. A 3-dimensional finite element model was developed in order to study the negative effect caused by stabilization of the fracture. The different results were obtained when considering a clinical case of a 35-year-old male patient. The results show the importance of fixation of symphysis fracture by two I-plates with four holes. The structural reliability level was estimated when considering a single failure mode and multiple failure modes. Conclusions: The integration of reliability concepts into mini-plate fixation strategy is considered a novel aspect. The reliability evaluation seams to be a reasonable asset in both convalescence and healing periods.
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| 4. |
- Ljubimova, Darja, et al.
(författare)
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Numerical study of the effect of vitreous support on eye accommodation
- 2005
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Ingår i: Acta of Bioengineering and Biomechanics. - 1509-409X. ; 7:2, s. 3-15
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the current work was to extend previously created finite element models of accommodation such as the one by BURD [2] by addition of vitreous. The zonule consisted of anterior and central sets and vitreous was modelled as a linear clastic incompressible body. An inverse method was used to find some important, previously not documented, aspects. The model was found to behave according to the expectations, with results consistent with classical Helmholtz theory.
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| 5. |
- Marusiak, Jaroslaw, et al.
(författare)
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Influence of number of records on reliability of myotonometric measurements of muscle stiffness at rest and contraction
- 2018
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Ingår i: ACTA OF BIOENGINEERING AND BIOMECHANICS. - : WROCLAW UNIV TECHNOLOGY, FAC COMPUTER SCIENCE & MANAGEMENT. - 1509-409X. ; 20:3, s. 123-131
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The aim of this study was to determine an effect of myotonometric records' number on stiffness measurements' reliability in muscles at rest and contraction. Methods: Muscle stiffness was measured using Myoton-3 device. Twenty records were taken for: (i) biceps (BB) and triceps brachii (TB) at rest and for BB at 10% of maximal voluntary contraction (MVC) in healthy elderlies (HE) and in Parkinson's disease patients (PD); and (ii) brachioradialis (BR) at rest and at 25, 50 and 80% MVC in healthy young (HY) subjects. Also, in HY group, the 3-records mode was used for BR's measurements at maximal contraction. Each measurement taken with 20-records was classed into five records groups: the whole 20- and the first 15-, 10-, 5- and 3-records. Test-retest reliability for these records groups was analyzed. Results: In HE and PD group measurements' reliability was excellent for all groups of records (20-3 records). In HY group, for the five groups of records taken at rest and submaximal levels of contraction (25, 50 and 80% MVC) the measurements reliability: (i) was mostly excellent or rarely average; and (ii) only in one per three 50% MVC conditions was unacceptable, i.e., for the 3-records group. The reliability of 3-records mode measurements at maximal contraction were unacceptable. Conclusions: Reliable myotonometric stiffness measurements in muscles at rest and during submaximal contractions can be achieved with less than 20 records (15, 10, 5 records) and even for the most of measurements with 3 records in HY and HE as well as in the PD patients. Myotonometric stiffness measurements with 3-records mode during maximal contraction were not reliable.
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| 6. |
- Xiao, Sen, et al.
(författare)
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Investigation of chest injury mechanism caused by different seatbelt loads in frontal impact
- 2017
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Ingår i: Acta of Bioengineering and Biomechanics. - 1509-409X. ; 19:3, s. 53-62
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this quantitative study is to investigate the differences of the injury mechanism caused by two different types of seatbelt loads on the occupant’s chest. Methods: The finite element analysis is employed to compare the different responses of the human body model, including comparison of kinematics, chest accelerations, seatbelt forces and chest injury outcomes regarding chest deflections and rib fractures. Results: The calculated rib strain-stress response from simulations in force-limiting seatbelt are higher than that in the regular seatbelt. The forward movement and torso twist are both great in simulations with force-limiting seatbelt. Moreover, there are obvious differences in the injury outcomes of chest deflections and rib fracture risks under the different seatbelt loads. Conclusion: Results indicate that the chest deflections and rib fracture risks are negatively correlated under the load of the force-limiting seatbelt, However, they are positively correlated to and determined by the seatbelt peak load of the regular seatbelt. This paper can provide a reference for study of the chest injury mechanism and protection efficiency of seatbelt.
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