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1

Charakterystyka mechaniczna rdzenia kręgowego świni pod wpływem obciążenia statycznego w badaniu in vitro

Pasławski R., Jacyna M., Jacyna K., Janiszewski A., Będziński R.

Inżynieria Powierzchni

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2018

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nr 2

43--48

PL

Podstawy: Pomimo faktu prowadzenia wielu badań wiadomo, że właściwości mechaniczne świńskiego rdzenia kręgowego poddawanego obciążeniom nie zostały jeszcze dostatecznie wyjaśnione. Metody: Próbki zostały obciążone przy różnych prędkościach odkształcenia: 0,02 (1/ s) i 0,002(1/ s)do wielkości odkształcenia od 5% do 10%. Po osiągnięciu określonej wartości odkształcenia próbki pozostawiono przy stałym odkształceniu po to aby utrzymać relaksację naprężeń. Wyniki: Testy rozciągania przedstawiające relację naprężenie-odkształcenie są znacząco nieliniowe z krzywą odpowiadającą niskiej sztywności. W poniższym obszarze naprężenie wzrasta wykładniczo wraz z przyłożonym odkształceniem. Największe wartości obliczonych naprężeń dla 10% odkształcenia wynosiły 0,014 MPa ( przy prędkości odkształcenia 0,02 (1/s)) i 0,008 MPa (przy prędkości 0,002 (1/s)).Liniowa aproksymacja naprężeń określona metodą minimum kwadratów pozwala wyznaczyć wartość modułu Younga: 39,68 kPa przy prędkości odkształcenia 0,02 (1/s) i 31,07 kPa przy prędkości odkształcenia 0,002 (1/s). Współczynnik statystyczny dopasowania R dla obu regresji miał wartość ponad 0,99 i potwierdził dobrą jakość aproksymacji. Współczynniki A i β (w równaniu Cloyd i Fujita) wynosiły odpowiednio 1,5 MPa i 31,3 przy prędkości odkształcenia 0,02 (1/s) oraz 1,3 MPa i 25,3 przy prędkości 0,002 (1/s). Względna relaksacja naprężeń została osiągnięta po 60 s w zakresie od 20% do 37%. Bezwzględna relaksacja naprężeń wynosiła od 0,4 kPa do 2,4 kPa przy prędkości odkształcenia 0,002 (1/s) przy 5 proc. maksymalnym odkształceniu oraz odpowiednio 0,02 (1/s) przy 10 proc. max. odkształceniu. Interpretacja: Charakterystyki mechaniczne przedstawiły też widoczną zależność odkształcenia i prędkości jako, że sztywność znacząco wzrasta wraz ze wzrostem prędkości odkształcenia.

EN

Background: In spite of a number of researchers, it is well known that mechanical behaviour of a spinal cord under loading has not yet been studied extensively enough. Methods: Specimens were loaded at various strain rates: 0.02/s and 0.002/s to 5% and 10% strain. After reaching defined strain value, samples were left at a constant strain for stress relaxation. Findings: The demonstrated tensile testing stress-strain response is a highly non-linear curve corresponding to low stiffness. In the toe region stress increases exponentially with the applied strain. The highest calculated stress value for 10% strain was 0,014 MPa (strain rate 0.02/s) and 0.008 MPa (strain rate 0.002/s). Linear approximation of the stress by the least square method allowed to derive Young modulus of the value: 39.68 kPa at strain rate 0.02/s and 31.07 kPa at strain rate 0.002/s. R squared value for both regressions was above 0.99 and confirmed a good quality of approximation. A and β coefficients (in Cloyd and Fujita equation) were 1.5 MPa and 31.3 at 0.02/s strain rates and 1.3 MPa and 25.3 at 0.002/s strain rates correspondingly. Relative stress relaxation increased from 20% to 37% after 60 s. Absolute stress relaxation was from 0.4 kPa to 2.4 kPa, at 0.002/s strain rate by 5% maximum strain and 0.02/s strain rate by 10% respectively. Interpretation: Mechanical characteristics demonstrated a visible strain-rate dependence as stiffness was significantly increasing with an increase of strain rate.

2

The influence of osteoporotic bone structures of the pelvic-hip complex on stress distribution under impact load

Arkusz K., Klekiel T., Niezgoda T. M., Będziński R.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 1

29--38

EN

Purpose: The aim of this study was to determine the effect of bone mineral density (BMD) on the stress distribution in pelvic-hip complex (PHC) model which included bone structures and soft tissues. Bone mass changes in osteoporosis and osteopenia were considered in this analysis. In addition, the relations between force direction and stress distribution causing PHC fractures were determined. Methods: This paper presents the development and validation of a detailed 3D finite element model with high anatomical fidelity of the PHC and BMD changes in trabecular and cortical bones, modelled based on CT scans. 10 kN loading was induced on a model consisting of 8 ligaments, the pelvis, sacrum, femur in front and side directions. Results: For validation, the results of this model were compared to physiological stress in standing position and previous results with high-energy crashes under side impact load. Analysis of side-impact indicated the influence of BMD on femoral neck fractures, acetabular cartilage and sacroiliac joint delaminations. Front-impact analysis revealed the inferior pubic ramus, femoral neck fractures and soft tissue injuries, i.e., acetabular cartilage and symphysis pubis in osteoporosis and osteopenia. Conclusions: The elaborated PHC model enables effective prediction of pelvis injuries in high-energy trauma, according to Young-Burgess classification, and the determination of the influence of BMD reduction on pelvis trauma depending on force direction. The correlation between BMD and stress distribution causing varying injuries was determined.

3

Modelling of damping properties of articular cartilage during impact load

Klekiel T., Będziński R., Wodzisławski J.

Engineering Transactions

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2017

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Vol. 65, iss. 1

133--145

EN

The paper presents some details about difficulties in modelling of articular cartilage. The most useful method to simulate a mechanism of tissue deformation during load is Finite Element Method (FEM). In this paper the authors present an approach of modelling a damping phenomenon in articular cartilage of an ankle joint. The damping property was modelled and analysed with an assumption that the reaction force is different suitable to change of a dynamic load. The model of lower extremity consists of three main bones: tibia, fibula and talus. The force acting on the model was generated from displacement of the talus according to the main biomechanical axis of a leg. The results present the role of an articular cartilage in distribution of energy inside the lower extremity. The analysis was carried out according to three main aspects: the reaction force in a support, the influence contact on the energy dissipation and the role of cartilage thickness in transmission of energy by the tibiotalar joint.

4

Biomechanical analysis of head injury causedby a charge explosion under an armored vehicle

Ratajczak M., Frątczak R., Sławiński G., Będziński R.

Computer Assisted Methods in Engineering and Science

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2017

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Vol. 24, no. 1

3--15

EN

In this study, the authors developed the numerical model of brain structure to assess brain injury of a person in military conditions. The numerical model aimed at analyzing changes in the mechanical parameters of brain structure in the conditions of rapid overload. The results of our investigation are intended to contribute to the explanation of the phenomena of degradation of brain structures among soldiers.

5

An analysis of the effect of impact loading on the destruction of vascular structures in the brain

Ratajczyk M., Sąsiadek M., Będziński R.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 3

21--31

EN

Subdural hematomas are one of the frequent complications of head injuries. Such hematomas result from exceeding the border strength values of bridging veins. Subdural haemorrhages are life-threatening and are a frequent cause of considerable pathologies. Traffic participants and also soldiers who participate in armed conflicts are the most vulnerable to head injuries. Although hematomas have been studied for many years the mechanism of hematoma formation has not been fully clarified as yet. In the paper, the effort of brain tissue structures due to the propagation of shock wave was analyzed. Particular attention was paid to the deformation ability and changes in the energy of bridging veins. This research was concerned with changes in mechanical properties of these veins in the frontal, parietal and occipital regions of the brain. For the present research the authors have constructed finite element models of brain tissue fragments and conducted numerical studies taking into account the boundary conditions arising from violent overloads that result from combat operations. As a result of the numerical analysis conducted, critical values of strain and stress have been obtained. The analysis showed high diversity in the properties of the different regions of the brain tissue. The studies carried out by the authors rendered it possible to assess the effort of the tissue structures of veins in connection with mechanical parameters, including geometrical parameters, in particular in relation to the likelihood of hematoma formation.

6

Numerical analysis of the risk of neck injuries caused by IED explosion under the vehicle in military environments

Mackiewicz A., Będziński R., Sławiński G., Niezgoda T.

Acta Mechanica et Automatica

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2016

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Vol. 10, no. 4

258--264

EN

As a result of an explosion under a military vehicle, the risk of threat to life and health of the crew increases. Examination of this event in terms of the security of soldiers comes down to a complex analysis of the mutual interaction of the body of a soldier, seating and structural elements of the vehicle. As a result, shock wave impacts can cause tremor resulting from the construction of the vehicle and acceleration of the passenger's body. This study attempts to analyze the impact of an explosion of an improvised explosive device (IED) under the military vehicle with the risk of cervical spine injuries of soldiers. The analysis was carried out using numerical methods in the LS-DYNA program and was carried out taking into account the variable displacement values and acceleration recorded during the\ explosion. The study used a model of the body of a soldier in the form of a Hybrid III 50th Male Dummy.

7

Analiza właściwości tłumiących chrząstki w stawie skokowym

Klekiel T., Będziński R.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2016

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Vol. 22, nr 4

198--206

PL

Niniejszy artykuł przedstawia analizę mechanizmu rozpraszania energii przez chrząstkę stawu skokowego człowieka. Wykonano analizę mającą na celu określenie prawdopodobieństwa powstawania urazu powierzchni stawowej pod wpływem obciążenia silnym impulsem. Opracowano model numeryczny stawu uwzględniający kość piszczelową, kość skokową, powierzchnie stawowe oraz więzadła. Sztywność układu uzyskano uwzględniając więzadła w postaci elementów sprężystych. Na podstawie opracowanego modelu, dokonano analizy wpływu zmian właściwości chrząstki i więzadeł na stopień tłumienia energii obciążenia. Wyniki badań numerycznych uwzględniają zarówno zmiany sztywności poszczególnych struktur, jak również zmiany modeli konstytutywnych materiałów użytych w modelu. Wyznaczono zależność pomiędzy strukturą geometryczną chrząstki a jej zdolnością do rozpraszania energii. Na drodze eksperymentów numerycznych wyznaczono warunki, przy których wystąpi uraz powierzchni stawowej.

EN

This article presents an analysis of the energy dissipation in the ankle during impact load. The aim of study was to analyze different material models of cartilage for selected conditions in which the contact of surface is destroyed. The numerical model includes tibia and talus with articular cartilage surfaces and ligaments. Based on the model, the changes in the material properties of cartilage were investigated for research the damping behavior of cartilage under impact load. The damping properties were analyzed based on the reaction force in the support. The differences in the force values were used for comparison of the selected material models. The numerical experiments show mechanism of destruction in the cartilage layer during plastic deformations. This destruction moment was detected by the yield stress of cartilage.

8

Safe rebuilding of the periodontal loss an experimental study

Minch L. E., Słowiński J. J., Scigala K., Będziński R., Kawala B.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2015

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Vol. 63, nr 2

527--532

EN

This study aimed at the simulation of bone tissue remodeling within a bone defect with the utilization of the finite element method (FEM), enabling - via elaborated application - objective evaluation of orthodontic forces which positively influence periodontium in vivo. The initial position of each bracket on the passive archwire was registered, and then a geometrical and discretemodel of the appliance was created automatically. Assessment of the dental scans obtained using cone beam computed tomography (CBCT) allowed evaluation of the range of bracket displacement: from the initial position to the final one achieved on the active archwire. Those displacements established terminal conditions in the finite element analysis, enabling calculation of orthodontic force levels. An individual design of a tooth with periodontal ligaments and the periodontal defect subsequently loaded with the determined forces allowed simulation of bone remodeling according to Carters adaptation process. Mainly, the bone apposition processes took place in the central part of the periodontal defect, in proximity of the alveolar ridge. However, FEM application in the analysis of bone tissue regeneration within bone defects enables precise evaluation of the achieved changes, therefore allows determination of orthodontic forces positively influencing periodontium in vivo.

9

Finite Element Analysis Of Large Deformation Of Articular Cartilage In Upper Ankle Joint Of Occupant In Military Vehicles During Explosion

Klekiel T., Będziński R.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3

2115-2121

EN

The paper presents the analysis of the load of lower limbs of occupants in the armoured military vehicle, which has been destroyed by detonation of the Improvised Explosive Device (IED) charge under the vehicle. A simplified model of the human lower limb focused on upper ankle joint was developed in order to determine the reaction forces in joints and load in particular segments during the blast load. The model of upper ankle joint, include a tibia and an ankle bone with corresponding articular cartilage, has been developed. An analysis of the stress distribution under the influence of forces applied at different angles to the biomechanical axis of a limb has been performed. We analyzed the case of the lower limb of a sitting man leaning his feet on the floor. It has been shown that during a foot pronation induced by a knee outward deviation, the axial load on the foot causes significantly greater tension in the tibia. At the same time it has been shown that within the medial malleolus, tensile stresses occur on the surface of the bone which may lead to fracture of the medial malleolus. It is a common case of injuries caused by loads on foot of passengers in armored vehicles during a mine or IED load under the vehicle. It was shown that the outward deviation of the knee increases the risk of the foot injury within the ankle joint.

PL

W artykule przedstawiono analizę MES obciążenia kończyn dolnych osób w opancerzonym pojeździe wojskowym, który został zniszczony przez zaimprowizowaną detonację ładunku wybuchowego (IED) pod pojazdem. W uproszczonym modelu dolnej kończyny ludzkiej skoncentrowano się na górnej części stawu skokowego. Model opracowany został w celu określenia siły reakcji w stawach i obciążenia w poszczególnych segmentach podczas obciążenia wybuchowego. Model górnego stawu skokowego, obejmuje kość piszczelową oraz kości stawu skokowego z odpowiadającymi chrząstkami stawowymi. Przeprowadzono analizę rozkładu naprężeń pod wpływem sił wywieranych pod różnymi kątami w stosunku do osi biomechanicznej kończyny. Przeanalizowano przypadek kończyny dolnej siedzącego mężczyzny z nogą opartą na podłodze. Wykazano, że podczas skręcenia stopy indukowanego przez odwiedzenie kolana na zewnątrz, siła osiowa na stopie powoduje znacznie większe naprężenie rozciągające w kości piszczelowej. Jednocześnie wykazano, że w kostce przyśrodkowej, naprężenia rozciągające występują na powierzchni kości, co może prowadzić do wystąpienia złamania kostki przyśrodkowej. Jest to częsty przypadek obrażeń spowodowanych obciążeniami stóp pasażerów pojazdów pancernych podczas eksplozji miny lub wybuchu ładunku (IED) pod pojazdem. Wykazano, że odchylenie kolana zwiększa ryzyko obrażeń stopy w stawie skokowym.

10

Biomechanical characteristics of the jump down of healthy subjects and patients with knee injuries

Mielińska A., Czamara A., Szuba Ł., Będziński R.

Acta of Bioengineering and Biomechanics

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2015

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Vol. 17, no. 2

111--120

EN

Purpose: The aim of this study is to investigate the drop jump performance of male patients who underwent ACLR and a control group using combined data acquisition system. Methods: A total of 28 male subjects aged 20 to 26 were studied: 22 did not show and were not diagnosed with any knee joint dysfunction (the control group) and six men who underwent ACLR of the left limb (group of patients). The control group was age, height and body mass matched. A data acquisition setup consisting of three independent modules including force platforms, position analysis system and electromyography was used. Subjects were jumping down from 0.1, 0.2, and 0.3 m step heights. The acquired signals were used to determine the ground reaction force, muscular activity, mass centre position, velocity and acceleration. Results: Statistically significant differences were found between the groups (t-test, p < 0.05) in the maximum vertical ground reaction force in the left limb for 0.2 and 0.3 m step heights. Differences in the muscle activity between the groups were found to be statistically significant (t-test, p < 0.05) before the jump, during the landing phase, and after the jump for selected muscle groups and step heights. Conclusion: Combing the three independent measurement systems provided new information on drop jump biomechanics. The distribution of loads in different muscles was not uniform across the groups. Patients allocated more energy to control their motion and seemed to protect their operated limb by shifting the bodyweight to the healthy limb.

11

Osteosynthesis on the basis of resorbable polymers implants - selected problems

Będziński R., Chłopek J., Frątczak R., Kotela I.

Engineering of Biomaterials

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2014

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Vol. 17, no. 128-129

108

EN

Use of bioresorbable materials in bone surgery opens up new possibilities in treatment of injuries and orthopaedic illnesses. Lack of necessity for implant removal surgery enables faster treatment and substantial reduction in costs of treatment. In recent years, these advantages have caused growing interest in materials of this type. It must be noted that bioresorbable materials in most cases are based on macromolecular materials – polymers which have completely different mechanical characteristics than traditional materials used in bone surgery. Bioresorbable properties give enormous possibilities but also present difficult challenges related to construction of new types of implants based on materials of this type. Full characteristics of new materials is indispensable in construction process, especially of mechanical properties and surface properties. The latter is responsible for contact with biological environment and bioactivity is determined on the basis of hydroxyapatite precipitations amount on material surface. In case of polymer based composites, influence of phases in powder and fibre form on properties is fundamental to be proved. Addition of particle modifier into polymer matrix causes reduction in strength of polymer. This phenomenon is mostly associated with homogenic particle distribution difficult to be achieved in case of higher filler content. However biological interplay is insufficient by low filler contents. Therefore in the below presented investigations different filler contents were applied and their influence on mechanical properties was investigated to achieve compromise between mechanical properties and bioactive, antibacterial or anti-inflammatory effect of the applied particles. Acquaintance with these results allowed for elaboration of full range of material and constructive solutions for implants in bone surgery. Biodegradable biopolymers have low mechanical properties (Young’s modulus, strength, viscoelasticity). Construction process of bioresorbable implants requires to be completely changed in way of conduction. Computer simulation based investigations of stress-strain characteristics is necessary to be carried out in each stage of research. Bigger cross-sections and different shapes of implants are required to achieve suitable stiffness. Application of bone screws made of resorbable materials requires design of these elements from the bottom up. Design of optimal shape of screw thread and point of contact between screw head and bone plate is particularly important. 9 different implants were designed within the confines of conducted research – including for tibia, humerus, radius, ulna, phalanges, clavicle, calcaneus, pelvis and metatarsus. Stress values were determined in analyzed implants. Acceptable loads were determined for individual types of plate. Plates made of PLA can bear small loads and play role mainly as grasping and holding bone element. In most cases additional immobilization of operated bone is required in order to prevent plate or screw destruction. In case of stabilization function for resorbable materials – as many screws as possible are recommended – thanks to it, screws are less loaded and the plate-bone system is more immobilized.

12

Survey of some constitutive models for arterial walls under uniaxial and biaxial loading

Jankowska M. A., Będziński R.

Vibrations in Physical Systems

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2012

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Vol. 25

177--184

EN

The paper deals with some constitutive equations for arterial walls subjected to uniaxial and biaxial extension tests. In spite of a great number of various approaches to development of the strain-stress relations, the models selected for presentation seems to be good representatives of the most characteristic and fundamental ones.

13

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.

14

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.

15

Comparative analysis of the deformation characteristics of biodegradable polymers considered as a material for vascular stents

Bartkowiak-Jowsa M., Będziński R., Chłopek J., Filipiak J., Szaraniec B.

Polimery

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2011

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T. 56, nr 3

224-231

EN

The research represents an attempt to find a polymer alternative to intravascular metallic implants. Materials were selected considering mechanical properties and deformation behavior of blood vessels, assuming that convergence regions of vessel and polymeric material strain characteristics ensure the uniformity of deformations at the implant/tissue interface and may reduce postimplantation side-effects. The findings of the research facilitated review the potential use of biodegradable polymers and their composites for the development of vessel stents; a successful attempt to create stent prototype using selected material has been made.

PL

Przeprowadzono badania właściwości mechanicznych biodegradowalnych polimerów bazowych oraz ich kompozytów z dodatkiem włókien lub proszków (tabela 1). Materiały selekcjonowano biorąc pod uwagę charakterystyki naprężeniowo-odkształceniowe naczyń krwionośnych (rys. 5), poszukując pokrywających się obszarów sprzyjających zachowaniu ciągłości odkształceń na granicy implant-tkanka (rys. 6, tabela 5). Materiałem wykazującym największą zbieżność pod względem charakterystyki naprężeniowo-odkształceniowej z tkanką naczyniową, w obszarze liniowym, jest poli(laktyd-ko-glikolid) (rys. 6b). Spośród materiałów o charakterystyce naprężeniowo-odkształceniowej typowej dla materiału ulegającego umocnieniu, największy stopień zbieżności uzyskano w przypadku kompozytów z dodatkiem włókien poliakrylonitrylowych (PAN) (rys. 6c) oraz alginianu sodu (NaAlg) (rys. 6d). Na podstawie przeprowadzonej analizy materiałowej wykonano prototyp stentu naczyniowego z polilaktydu PL(DL)A z długim włóknem alginianowym (rys. 7). Udało się uzyskać implant o zamierzonych wymiarach i założonej charakterystyce geometrycznej.

16

Właściwości mechaniczne i przebieg degradacji kompozytów PLA/włókna alginianowe

Bartkowiak-Jowsa M., Kwiatkowska A., Szaraniec B., Chłopek J., Będziński R., Witkiewicz W.

Engineering of Biomaterials

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2011

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Vol. 14, no. 106-108

164--166

17

Elastin and collagen fibres alterations for abdominal aortic aneurysms population with constant maximum diameter size

Kobielarz M., Maksymowicz K., Będziński R.

Engineering of Biomaterials

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2011

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Vol. 14, no. 102

2--6

EN

Development of abdominal aortic aneurysm (AAA) is a dynamic process proceeding as a result of the multi-factor pathological remodelling of elastin and collagen fibres, results an aneurysm expansion. In clinical practice, development of AAA is identified with aneurysm growth. Hence, the aim of this paper is to propose a taxonomy of load-bearing structural components alterations for AAA with relatively constant maximum diameter (average diameter 6.9±0.8 cm). Structural investigations of normal (n=47) and aneurismal (n=46) vessels were carried out on the basis of histological and ultrastructural examinations. The histological preparations were subjected to histometric evaluation; the number of collagen and elastin fibres and additionally the thickness of the particular vascular wall layers. A qualitative analysis of the abdominal aortic wall, mainly estimation of fibres arrangement, based on histological and ultrastructural (SEM) examinations were additionally performed. Using a cluster analysis, three stages of load-bearing fibres alterations for AAA population were distinguished. The clusters were systematized according to NAA results. For AAA population with relatively constant maximum diameter in the first stage of load-bearing fibres remodeling was observed a substantial loss of elastin fibres. The second stage is characterized by an increase in the number of collagen fibres. In the final stage the number of collagen is dramatically reduced. Presented results provide evidence to risk of AAA rupture is not connected with AAA size but a remodelling of extra-cellular matrix proteins. The remodelling is accompanied by changes in the AAA wall thickness, which should be taken into consideration when evaluating the degree of advancement of this disease.

18

Mechanobiology of soft tissues: FT-Raman spectroscopic studies

Gąsior-Głogowska M., Komorowska M., Hanuza J., Mączka M., Będziński R., Kobielarz M.

Challenges of Modern Technology

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2011

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Vol. 2, no. 3

8--11

EN

FT-Raman spectroscopy was used to investigate microstructural changes in the secondary protein structure of soft tissues subjected to increasing levels of macroscopic strain. Main protein bands at 938 cm-1 assigned as v(Cα–C), 1668 cm-1 — amide I and 1268 cm-1 — amide III are sensitive to applied strain and undergo wavenumber shifting. Other main vibrational modes at 1004 cm-1 assigned to the phenyl ring breathing mode and 2940 cm-1 (n(CH3,CH2)) remain unaltered. Spectroscopic results were compared with the mechanical relations obtained from the standard protocol of uniaxial tensile tests carried out in a testing machine. A clear correlation between Raman band shifting and the level of mechanical stress was established. Initially the load is transferred through elastin and then gradually also by collagen. It was proved that transferring loads by soft tissues involves changes in structural protein conformation. This process was described in detail for a tendon. It was also confirmed that mechanical properties of soft tissues depend on collagen and elastin fiers orientation.

19

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.

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The structure optimization of implants materials of the surface layers by sol-gel coating

Donesz A., Krzak-Roś J., Kochanowska I., Będziński R.

Aktualne Problemy Biomechaniki

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2011

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z. 5

25--28

EN

This work presents the synthesis of fluorine- and chlorine-doped silica thin films on stainless steel (316L) prepared by the sol–gel method. Obtained materials were examined: structurally (SEM, roughness measurements), mechanically (four-point bending test) and biologically (in vitro). The results of the tests show that it is a possibility to synthesis by sol-gel method stable, continuous and biocompatible coating for materials used for implants.