Wyniki wyszukiwania - BazTech

1

Biomechanics of distal femoral fracture fixed with an angular stable LISS plate

Pakuła G., Słowiński J., Ścigała K.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 4

57--65

EN

Fractures of the distal end of the femur are infrequent and constitute less than 1% of all fractures. Only 3% to 6% of femoral fractures occur at the distal end. The two groups most at risk of the said fractures are young men and older women. The aim of treatment of fractures of the distal femur is to restore normal function of the knee joint. The authors asked themselves whether, following fixation of a 33-C2 fracture (according to the AO classification) with a LISS plate, a rehabilitation program can be undertaken immediately after surgery with the implementation of active movements in the knee joint of the operated limb. In order to answer this question, we created a digital model of a fractured femur fixed with the LISS method. The model was subjected to loads corresponding to the loads generated during active lifting of a limb extended in the knee joint and during flexing of a limb in the knee joint to the 90° angle. Interfragmentary movement (IFM) is one of the key parameters taken into account in the treatment of bone fractures. It allows classification of the treatment in terms of its quality both from the mechanical and histological points of view. We analyzed interfragmentary movement in all fracture gaps. The largest recorded displacement reached in our model was 243 μm, which, in the light of the literature data, should not interfere with bone consolidation, and thus implementation of active movement in the operated knee joint (keeping in mind the simplifications of the experimental method used) is possible in the early postoperative period.

2

Analysis of the influence of a metha-type metaphysical stem on biomechanical parameters

Pozowski A., Ścigała K., Kierzek A., Paprocka-Borowicz M., Kuciel-Lewandowska J.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 2

13--20

EN

The full postoperative loading of the limb is possible if patients are properly selected and qualified for hip arthroplasty and the requirements as to the proper position of the metaphysial stem are met. The lack of precision, and patient qualification which does not satisfy the fixed criteria may result in stem setting inconsistent with the assumptions. An analysis based on the finite element method (FEM) will enable one to find out how to plan the magnitude of operated joint loading on the basis of the position of the stem in the postoperative radiograph. By analyzing the distribution of bone tissue deformations one can identify the zones where the spongy bone is overloaded and determine the strain level in comparison with the one determined for a model of the bone with the stem in proper position. On the basis of the results obtained one can estimate the range of loads for the operated limb, which will not result in the loss of the stem’s primary stability prior to obtaining secondary stability through osteointegration. Moreover, an analysis of the formation of bone structures around the stem showed that the incorrect setting of a Metha-type stem may lead to the initiation of loosening.

3

Mechanical properties of cervical dura mater

Mazgajczyk E., Ścigała K., Czyż M., Jarmundowicz W., Będziński R.

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 1

51-58

EN

The aim of the study was to determine experimentally the stress as strain function as well as the orthotropy and heterogeneity of porcine dura mater of the cervical spinal cord. Material was divided into groups based on the place of collection, considering the dorsal side and ventral side, specifying the number of cervical vertebra, and the direction of tension of the sample - longitudinal or circumferential. Experimental studies were conducted with the MTS Synergie 100 testing machine. The tensile test was performed for each sample at a speed of 2 mm/min until the sample's break. There were determined the characteristics of stress as a function of strain in particular samples. Distribution maps of the stress and strain values at the characteristic points were then drawn (the beginning and the end of the linear range of the stress-strain characteristic and the point corresponding to the complete sample damage) for each set of samples, taking account of their collection place and direction of tension. The results confirmed the orthotropy of mechanical properties of dura mater. Stress and strain differed also in the value at the height of each vertebra and exhibited diversification on the ventral side compared to dorsal one.

4

Finite element modelling of the cervical spinal cord injury - clinical assessment

Czyż M., Ścigała K., Będziński R., Jarmundowicz W.

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 4

23-29

EN

The aim of the study was to evaluate the efficiency of Finite Element Method (FEM) modelling of the clinical cases of traumatic cervical spinal cord injury (SCI). The study population consisted of 28 patients suffering from traumatic cervical spine injury with (study group) and without (control) neurological deficits. A numerical simulation of the trauma event was performed, based on validated 3D FEM model. All the results obtained underwent statistical analysis. Statistically significant differences between both groups were found in severity of bony and neural structure damage as well as in stress and strain ratios. The highest values of tensile stress and deformation were noted in the sagittal (Y) axis. The maximum stress and strain were found in anterior spinothalamic, lateral spinothalamic and dorsal columns. It was also found that stress and strain in each segment and axis of the spinal cord model were positively correlated with the severity of the cervical spine injury (R-Spearman 0.39 to 0.64) and neurological symptoms of SCI (R-Spearman: 0.43 to 0.82). It is possible to create a clinical numerical model of the SCI with the use of FEM. The correlations between the mechanical force and neurological deficits show tendencies which require further studies based on an improved model and a greater number of patients.

5

Application of generative technologies in the design of reduced stiffness stems of hip joint endoprosthesis

Ścigała K., Będziński R., Filipiak J., Chlebus E., Dybała B.

Archives of Civil and Mechanical Engineering

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2011

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Vol. 11, no 3

753-767

EN

This paper presents proposed new design solutions for hip endoprosthesis stems characterised by reduced stiffness as a result of application of internal lattice structures obtained using generative production techniques. The conducted analysis showed the possibility of achieving lattice structures inside implants as well as the possibility of controlling mechanical characteristics of the end forms of implants. It was demonstrated that the use of inner lattice structures resulted not only in reduced implant stiffness, but also in reduced formation of adverse cancellous tissue trabecular structures. The obtained results indicate that it is possible to obtain implant structures that are much less vulnerable to the stress shielding effect than traditional designs.

PL

W pracy przedstawiono nowe rozwiązania konstrukcyjne trzpieni endoprotezy stawu biodrowego charakteryzujące się obniżoną sztywnością uzyskana przez zastosowanie ażurowych konstrukcji wewnętrznych. Konstrukcje tego typu są otrzymywane przez zastosowanie generatywnych technik wytwarzania. Przeprowadzona analiza wykazała zarówno możliwość uzyskania konstrukcji ażurowych w bardzo szerokim zakresie jak również możliwość sterowania charakterystykami mechanicznymi końcowych postaci implantów. Wykazano, iż zastosowanie wewnętrznych konstrukcji ażurowych prowadzi nie tylko do zmniejszenia sztywności implantu, lecz również prowadzi do zmniejszenia efektu kształtowania się wokół implantu niekorzystnych struktur beleczek tkanki gąbczastej. Uzyskane wyniki wskazują na potencjalną możliwość uzyskania konstrukcji implantów w znacznie mniejszym stopniu narażonych na efekty "stress shieldingu" niż konstrukcje tradycyjne.

6

Numerical model of the human cervical spinal cord - the development and validation

Czyż M., Ścigała K., Jarmundowicz W., Będziński R.

Acta of Bioengineering and Biomechanics

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2011

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Vol. 13, no. 4

51-58

EN

The influence of mechanical load on the extent of nervous tissue damage in the spinal cord at the time of trauma is presently incontestable. Although numerical modelling cannot fully replace physical testing, it seems to be the perfect complement to experiments in terms of the analysis of such a complex phenomenon as traumatic spinal cord injury. Previous numerical models of the human cervical spinal cord have been limited by several factors: two-dimensional modelling, spinal cord geometry simplification and incomplete reflection of specific anatomical and biomechanical relations of the objects being modelled. The objective of this study was to develop and validate an accurate and universal numerical Finite Element Method (FEM) model of the human cervical spinal cord. Our survey focuses mainly on geometric, constraint and material aspects. Experimental validation was carried out based on a controlled compression of the porcine spinal cord specimens. Each stage of compression was simulated using the FEM model of the compressed segment. Our 3D numerical simulation results compared with experimental results show a good agreement. It is possible to use the developed numerical model of the human cervical spinal cord in the biomechanical analysis of the spinal cord injury phenomenon. However, further clinical evaluation is clearly justified.

7

Impact of some external factors on the values of mechanical parameters determined in tests on bone tissue

Nikodem A., Ścigała K.

Acta of Bioengineering and Biomechanics

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2010

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Vol. 12, no. 3

85-93

EN

The knowledge of the mechanical characteristics of bone structures is a prerequisite for theoretical, numerical, and experimental analyses describing the functioning of bone, which is a living organ. The description of the mechanical properties of bone tissue, such as conventional Young’s modulus or strength, will enable the assessment of the degree of tissue degeneration through a comparison of the material properties of the examined bones to the properties determined for physiologically normal bones. However, the mechanical parameters published by different research centres often differ from each other by up to several hundred percent. These discrepancies arise primarily from the differences in the research methodology applied, and thus from many additional factors having a direct impact on the values of the mechanical parameters obtained in experimental tests. Therefore, in order to standardize and improve the interpretation of the results of measurements, we should develop universal criteria for the measuring conditions and quantify the impact of the factors being related to sample and measurements on the values obtained. In this paper, the authors present the dependence of some factors, i.e. the site and direction of sample excision as well as the rate and type of loading, on the values of the mechanical parameters. Those values were determined in experimental tests and the additional correlation coefficients proposed enabled an easier comparison of the results obtained with the values presented in the literature.

8

The biomechanical analysis of the traumatic cervical spinal cord injury using Finite Element approach

Czyż T., Ścigała K., Jarmundowicz W., Będziński R.

Acta of Bioengineering and Biomechanics

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2008

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Vol. 10, nr 1

43-54

EN

According to up-to-date knowledge only mathematical modelling of the spinal cord injury (SCI) may provide real insight into a spatial location of the fields of the spinal cord mechanical strain generated by the injury. The purpose of our research was to correlate the results of Finite Element Analysis of SCI with the patient’s neurological state and the injured spinal cord MR imaging. The 3D Finite Element Model of the cervical spinal cord and vertebral canal of a 21-year-old male patient was created. The moment of the injury was reconstructed by a simulation of the displacement of nonelastic structure to the light of vertebral canal. A detailed spatial analysis of the stress, strain and dislocation distribution was performed. The most injured region was the superficial zone of the white matter, the anterior part and central region of the grey matter, which was in good agreement with patient’s neurological staus. An individualized Finite Element Model of traumatic SCI constructed by us enabled the evaluation of the influence of mechanical strain on a neurological condition of a patient. Further research will consist in validation of the results of endurance analyses based on a enlarged group of patients.

9

Badanie właściwości mechanicznych i histomorfometrycznych tkanki kostnej kości udowej człowieka

Będziński R., Ostrowska A., Ścigała K., Mazurkiewicz A.

Inżynieria Biomateriałów

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2005

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R. 8, nr 47-53

78--80

10

Zastosowanie MES do modelowania regeneratu kostnego

Filipiak J., Ścigała K.

Systems : journal of transdisciplinary systems science

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2004

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Vol. 9, No. sp. I

378-384

PL

Przedstawiono wstępne badania symulacyjne MES dotyczące analizy pola odkształceń i ciśnienia hydrostatycznego w regeneracie kostnym powstałym w wyniku wydłużania kości. Analizowano wpływ osiowych i poprzecznych przemieszczeń odłamów kostnych na rozkład odkształceń w przestrzeni międzyodłamowej. Uzyskane z przeprowadzonych symulacji wyniki pokazują, że szczególnie poprzeczne przemieszczenia odłamów kostnych generują w regeneracie kostnym złożony stan odkształcenia charakteryzujący się zróżnicowaniem zarówno, co do wartości jak i charakteru oraz dużym gradientem zmian.

EN

The aim ofthis paper is preliminary FEM simulations present. This study concern strain and hydrostatic pressure analysis in callus on the function of bone fragments displacements. Axial bone fragments displacements take into consideration. On the basis of FEM simulations one may say thai axial displacements of bone fragments very difficult slate of strain and hydrostatic pressure generale, This slate of strain and hydrostatic pressure are very diverse for the sake of his character and value.

11

Symulacja numeryczna procesu tworzenia się struktury beleczkowej kości gąbczastej

Ścigała K., Kiełbowicz A., Słowiński J.

Systems : journal of transdisciplinary systems science

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2004

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Vol. 9, No. sp. II

827-832

PL

Przedstawiono wyniki analizy procesu tworzenia się struktur beleczek kości gąbczastej pod wpływem obciążenia na drodze adaptacji funkcjonalnej. W pracy analizowano nie ty!ko zgodność uzyskanych struktur pod względem ich kształtu, roziożenia i wymiarów lecz również charakterystyk mechanicznych. Uzyskane wyniki wskazują iż zastosowana procedura umożliwiają uzyskanie struktur zbliżonych do rzeczywistej kości również pod względem ich właściwości mechanicznych.

EN

Presented paper is focused on the simulation of modelling process of trabcculae structure of canceilous bone. Existing algorithm of process was adapted to create structures of overloded, normal an unloaded structure. Analysis was focused on the verification of similarity of mechanical properties of created structure and real bone tissue.

12

Investigation of Mechanical Structure of Long Bone

Będziński R., Ostrowska A., Ścigała K.

Machine Dynamics Problems

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2004

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Vol. 28, No. 3

45-50

EN

The main aim of this paper is identification of bone mechanical and structural properties by strength testing, investigations of properties anisotropy and microscopic examination. Mechanical testing in compression was used for investigation of yield stress, yield strain, maximum strength and elasticity modulus values for bone samples dissected form human and bovine femur bones. Optical methods of displacement distribution analysis were used for investigations of Young modulus in bending for various levels of bone specimens dissection. Microscopic investigations allow to examine lamellae orientation and its influence on the mechanical properties and remodelling processes. Results shows possibilities and necessities of extension of existing models of bone adaptation.

13

A Study of Human Skull Deformation by Using Laser and CT Method

Szotek S., Będziński R., Ścigała K., Ciupik L.

Machine Dynamics Problems

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2004

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Vol. 28, No. 4

133-138

EN

The purpose of the conducted research was a biomechanical analysis of occipito-cervical stabilisation including an estimation of occiput bone dislocation as well as the examination of the anchor-bone connection endurance. An experimental analysis of displacements' distribution on the surface of bone preparations was carried out, in the analysis post-mortem preparations with an inserted implant were used. An analysis of displacements registered on the same stabilizer was carried out, too. Measurements methods used in the research were computer tomography (CT), Electronic Speckle Interferometry (ESPI) and holographic interferometry.

14

Przemieszczenia odłamów kostnych jako czynnik determinujący rozwój regeneratu kostnego

Filipiak J., Ścigała K.

Inżynieria Biomateriałów

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2004

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R. 7, nr 38-42

136-138

15

Analiza stanu przemieszczeń i odkształceń kości piszczelowej dla różnych modeli materiału tkanki kostnej

Ścigała K., Niciński T.

Inżynieria Biomateriałów

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2004

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R. 7, nr 34

9-13

16

FEM analysis of strain distribution in tibia bone and relationship between strains and adaptation of bone tissue

Będziński R., Ścigała K.

Computer Assisted Mechanics and Engineering Sciences

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2003

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Vol. 10, No. 3

353-367

EN

The purpose of the research is the estimation of strain distribution in tibia bone. Resultant strain distribution constitutes necessary data for the calculations made in the process of simulation of bone tissue adaptation. Estimation of strain distribution in proximal part of tibia bone is made for different load conditions (including the one following total knee arthroplasty and a surgical correction of lower limb with the application of high tibial osteotomy). The model of tibia bone and soft tissues, prepared for finite element analysis, was made with the use of Ansys 5.6. The geometry of bone was estimated by 3-D digitalisation of a physical model of bone. Displacements distribution obtained from the simulation was compared with the measurements of the physical model of a knee joint. In the research the holographic interferometry method was applied. The results of this calculation are helpful in the estimation of boundary conditions for a simulation of bone tissue functional adaptation in the region of a knee joint. It has been found out that there are differences in strain distribution in different load conditions. However, the perfect agreement of experimental and numerical results for a simple static load indicates that the numerical model is valid for this simulation in a certain range of the applied load.

17

Analiza kliniczna i biomechaniczna osteotomii walgizującej "minus" wykonywanej w odcinku międzywęzadłowym piszczeli

Pozowski A., Ścigała K.

Inżynieria Biomateriałów

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2001

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R. 4, nr 14

14-21

18

Sress distribution in varus knee after operative correction of its mechanical axis

Pozowski A., Będziński R., Ścigała K.

Acta of Bioengineering and Biomechanics

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2001

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Vol. 3, nr 2

31-40

EN

An analysis of the results of 121 minus-valgizing osteotomies in genu varum performed in the years 1985-1998 allowed the authors to conclude that the recommended by most researchers hyper-corrective valgus positioning of the knee's mechanical axis after an osteotomy resulted in increased postoperative valgity in 12 cases. This complication nullified the intended effect of the operation and required another corrective procedure. Clinical observations showed that the probable causes of the complications could be different, e.g. a significant decrease of bone density in the joint's exterior section, taking over the body-weight load, and the patient's considerable overweight. Whereas the presumptive cause was a limited capability of remodelling of the overloaded exterior section of the joint. In order to determine the magnitude and distribution of static forces in the knee's articular ends, a series of measurements were made using spatial photoelastic models as exact geometrical copies of specimens from autopsy. The measurements have shown that in the case of the hypercorrective position of the joint's axis, an extremely heavy concentration of forces occurs on the relatively small bearing surface of the outer condyle of the tibia. This creates adverse mechanical conditions and makes it impossible to obtain the intended correction angle.

19

Badania modelowe stanu naprężeń i odkształceń w stawie kolanowym z zaimplantowaną endoprotezą bezcementową

Ścigała K., Bernakiewicz M., Będziński R., Chmielarczyk P.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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1999

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z. 9

255-260

PL

W niniejszym opracowaniu przedstawiono wyniki analizy numerycznej modelu stawu kolanowego z wprowadzoną endoprotezą bezcementową typu kłykciowego, prowadzonej przy użyciu metody elementów skończonych Wyniki analizy posłużyły do analizy wytrzymałościowej elementów protezy, jak również do określenia prawdopodobieństwa powstania obluzowań komponentu piszczelowego.

EN

Numerical analysis results of knee joint model with implanted policentric, non-cemented endoprosthesis using finite element method is presented in this paper Stress and strain distributions in bone tissue are base of calculation of probability of prosthesis survivorship.

20

BIomechanical aspects of artificial joint implantation in a lower limb

Będziński R., Bernakiewicz M., Ścigała K.

Journal of Theoretical and Applied Mechanics

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1999

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nr 3

455-479

EN

One of the most important trends in engineering biomechanics is experimental and numerical analysis of the stress and strain state existing in organs subject to a heavy load; e.g., the knee and hip joints. Clinical tests experimental and numerical studies on design of implants replacing damaged organs are also of crucial importance in development of biomechanics. The research is focused on determination of loads, experimental techniques as well as on simplifications assumed in measurements and applied models. The conducted investigations were concerned with estimation of mechanical behaviour of hip and knee implants after arthoplasty. The experimental tests on both the real objects and models were performed. Numerical simulation was made by using the finite element method. The tests have proved that from the biomechanical point of view proper selection of endoprothesis is of crucial importance for achieving positive long-term results of alloplasty.

PL

Jednym z najważniejszych kierunków badań w dziedzinie biomechaniki inżynierskiej jest doświadczalna i numeryczna analiza stanu odkształceń i naprężeń w organach ludzkich poddanych znacznym obciążeniom, jak chociażby staw biodrowy i kolanowy. Badania kliniczne, doświadczalne i numeryczne poświęcone konstrukcji elementów zastępujących uszkodzone elementy ciała ludzkiego stanowią jeden z najważniejszych kierunków biomechaniki. Dyskusje na tym tle skoncentrowane są na problemach beterminacji występującego stanu obciążenia, stosowanych technik pomiarowych oraz uproszczeń warunków pomiaru i przyjmowanych modeli. Przeprowadzone badania poświęcone zostały ocenie mechanicznej współpracy sztucznych elementów stawu biodrowego i kolanowego w warunkach modelowych, jak i metodą symulacji numerycznej, metodą elementów skończonych. Badania udowodniły duże znaczenie prawidłowej selekcji endoprotez z punktu widzenia biomechaniki układu na długoterminowe powodzenie alloplastyk.