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1

The assessment of temperature amplitude arising during the implant bed formation in relation to variable preparation parameters – in vitro study

Kosior Piotr, Nikodem Anna, Kozuń Marta, Dudek Krzysztof, Janeczek M., Dobrzyński Maciej

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 3

163--173

EN

The main purpose of this study was to analyse the temperatures generated during the bone bed preparation, given the internal structure of the bone bed, the geometry of the hole, and the treatment parameters such as the type of cooling and the rotational speed of the drill. The investigated material was domestic pig ribs, in which holes were drilled three times using two drill bit systems used for Hiossen® and Paltop® dental implantation. The ThermaCAM® P640 thermal imaging camera was used for measurement of drilling temperatures. After the holes were drilled, each rib was examined using the 1172 SkyScan microtomograph, Bruker®, to compare the geometry of the machined holes. The presented study proved that larger diameter drill bits (Hiossen® drill bits) generate more heat during the machining process, as evidenced by higher temperatures obtained for the Hiossen system in each case. It was proved that rotational speed, drill bit diameter and cooling system have a significant effect on the amount of heat generated during bone tissue preparation. The density and type of bone tissue in which the hole is prepared are significant factors affecting the amount of heat generated.

2

Experimental evaluation of a novel concept of an implant for direct skeletal attachment of limb prosthesis

Prochor Piotr

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 4

3--13

EN

Purpose: The aim of the study was to experimentally evaluate a proposed two-part implantation system (medullary part made of PEEK composite and percutaneous part made of Ti6Al4V) for bone-anchored prosthesis and to compare it to typical press-fit design (also made of Ti6Al4V) used for the same purpose. Methods: Simplified prototypes of both implants were prepared for the research. Both implants were evaluated in vitro with the use of porcine femur (6 bones for each implant). ARAMIS vision system was used to measure strains in selected area of bone shaft, generated when putting an axial load on the implants to simulate static load bearing exercises performed during rehabilitation activities in primary stabilisation. Results: Obtained maps revealed high concentrations of strains, located near to distal part of the implant, during using a typical press-fit design with relatively low strain around the implant’s shaft. In the case of proposed design, noticeable strains occurred in the entire examined area of bone, with stronger concentration towards the proximal direction. Conclusions: Presented experimental results suggest that proposed design provides more appropriate implant-bone load transfer than typically used press-fit design. This may result in obtaining more beneficial mechanobiological stimulus which enables the researchers to achieve appropriate primary stability and maintain appropriate bone quality during its long-term use after achieving full osseointegration.

3

A 3D trabecular bone homogenization technique

Marques Marco Costa, Belinha J., Oliveira A. F., Manzanares Cespedes M.C., Natal Jorge R.M.

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 3

139--152

EN

Purpose: Bone is a hierarchical material that can be characterized from the microscale to macroscale. Multiscale models make it possible to study bone remodeling, inducing bone adaptation by using information of bone multiple scales. This work proposes a computationally efficient homogenization methodology useful for multiscale analysis. This technique is capable to define the homogenized microscale mechanical properties of the trabecular bone highly heterogeneous medium. Methods: In this work, a morphology-based fabric tensor and a set of anisotropic phenomenological laws for bone tissue was used, in order to define the bone micro-scale mechanical properties. To validate the developed methodology, several examples were performed in order to analyze its numerical behavior. Thus, trabecular bone and fabricated benchmarks patches (representing special cases of trabecular bone morphologies) were analyzed under compression. Results: The results show that the developed technique is robust and capable to provide a consistent material homogenization, indicating that the homogeneous models were capable to accurately reproduce the micro-scale patch mechanical behavior. Conclusions: The developed method has shown to be robust, computationally less demanding and enabling the authors to obtain close results when comparing the heterogeneous models with equivalent homogenized models. Therefore, it is capable to accurately predict the micro-scale patch mechanical behavior in a fraction of the time required by classic homogenization techniques.

4

Temperature controlled dual hypoxic chamber design for in vitro ischemia experiments

Bagó M., Horváthy D. B., Simon M., Marschall B., Pinto A., Kuten O., Polsek D., Hornyák I., Nehrer S., Lacza Z.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 3

498--503

EN

In vitro ischemia models are designed to study various aspects of hypo-perfusion, focusing on the consequences of acute events under body temperature. Cold ischemia is less investigated even though the beneficial effects of cooling is expected. The aim of the present work was to develop a device modeling cold and warm ischemia in vitro. Oxygen-glucose deprivation was applied with continuous nitrogen flow and glucose-free cell culture media to mimic ischemia. The temperature in both chambers were independently set between 4 and 37 °C. Samples were placed inside for the ischemic period, followed by a reperfusion stage under standard cell culture conditions. We tested rat calvaria bone pieces undergoing 1, 7, 12 and 24 h of ischemia at 4 and 37 °C. After 24 h of reperfusion, cell number was measured with a tetrazolium cell viability assay. One hour of warm ischemia paradoxically increased the post-reperfusion cell count, while cold-ischemia had an opposite effect. After 7 h of warm ischemia the cells were already unable to recover, while under cold ischemia 60% of the cells were still functioning. After 12 h of cold ischemia 50% of the cells were still be able to recover, while at 24 h even the low temperature was unable to keep the cells alive. The markedly different effect of warm and cold ischemia suggests that this newly designed systemis capable of reliable and reproducible modeling of ischemic conditions. Moreover, it also enables deeper investigations in the pathophysiology of cold ischemia at cellular and tissue level.

5

Role of initial density distribution in simulations of bone remodeling around dental implants

Nutu E.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 4

23--31

EN

In this paper, the effect of initial density distribution upon the predicted density via numerical simulations of bone remodeling was evaluated. The main purpose was to correlate the numerical results with clinical data according to which the initial bone quantity is an essential factor for long term survival of dental implants. Methods: Two-strain energy density-based bone remodeling theories were employed, one which accounts for overload resorption and the second one, which does not. The remodeling parameters were derived from the mechanostat theory. Bone remodeling around an osseointegrated dental implant was simulated based on finite element method using a generic mandible plane model. A variable time step was introduced to increase the speed of the remodeling simulations by keeping the truncation errors small. The simulations were performed for several initial density distributions correlated with values from clinical classifications of bone quality. For each density value, the occlusal load was defined in two ways so that to consider normal and overload mastication forces, respectively. Results: The results showed that the initial density distribution influences the predictions of bone remodeling simulations. For the analyzed model, the remodeling algorithm predicted overload resorption only in the case of low initial density, which can be associated with low bone quality, which, from clinical perspective, may probably lead to implant loss. Conclusions: The paper demonstrated that when simulating bone remodeling around dental implants using finite element method, it is important to account for initial density distribution in correlation with the bone quantity.

6

Numerical analysis of the foods nature effect on the mechanical behavior of dental implants

Sifi M., Serier B., Merdji A., Benaissa A, Mootanah R.

Mechanics and Mechanical Engineering

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2017

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Vol. 21, nr 4

1021--1032

EN

This study focuses on a three-dimensional numerical analysis by the finite element method, the mechanical behavior of the dental prosthesis implant composed of a single implant. The effect of the nature of food on the level and distribution of the Von Mises equivalent stress generated in the bone and the elements that constitute this prosthesis have been highlighted. It has been shown that this level is particularly important that the Crushed masticated foods are rigid. This work was carried out to answer questions whose purpose was to analyze the risk of overload in the mandibular region. Loads transfer mechanisms and the possible failure of osseointegrated implants, the shape of the implant, the geometrical and mechanical properties of the placement site and bone resorption of the crest. A proper estimation of these effects allows the correct design of the implant.

7

Zjawiska elektryczne w kościach jako efekt piezoelektryczności hydroksyapatytu

Pawlikowski M.

Auxiliary Sciences in Archaeology, Preservation of Relics and Environmental Engineering

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2017

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nr 22

1--9

PL

Wykonane badania biomineralogiczne wskazują na piezoelektryczne właściwości apatytu, który jest jednym z głównych składników kości. Publikacja prezentuje hipotetyczne zależności między piezoelektrycznymi właściwościami apatytu kostnego i towarzyszącymi zjawiskami elektromagnetycznymi w kościach i ich otoczeniu. Zwraca uwagę na relacje – właściwości elektryczne kości – zmiany pola elektromagnetycznego wokół kości oraz na relacje zewnętrzne zmiany ciśnienia i in. – zjawiska elektryczne w kościach.

EN

Conducted biomineralogical studies indicate piezoelectric properties of apatite, which is one of the major components of bone. This publication presents hypothetical correlations between piezoelectric properties of bone apatite and the accompanying electromagnetic phenomena in bones and their environment. It notes the correlations between electrical properties of bones and changes in the electromagnetic field around bones, as well as connections between external pressure changes etc. and electrical phenomena in the bones.

8

Experimental analysis of insertion torques and forces of threaded and press-fit acetabular cups by means of ex vivo and in vivo measurements

Vogel D., Rathay A., Teufel S., Ellenrieder M., Zietz C., Sander M., Bader R.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 3

155--163

EN

In THA sufficient primary implant stability is the precondition for successful secondary stability. Industrial foams of different densities have been used for primary stability investigations. The aim of this study was to analyse and compare the insertion behaviour of threaded and press-fit cups in vivo and ex vivo using bone substitutes with various densities. Methods: Two threaded (Bicon Plus®, Trident® TC) and one press-fit cup (Trident PSL®) were inserted by orthopaedic surgeons (S1, S2) into 10, 20 and 31 pcf blocks using modified surgical instruments allowing measurements of the insertion forces and torques. Furthermore, the insertion behaviour of two cups were analysed intraoperatively. Results:Torques for the threaded cups increased while bone substitute density increased. Maximum insertion torques were observed for S2 with 102 Nm for the Bicon Plus® in 20 pcf blocks and 77 Nm for the Trident® TC in 31 pcf blocks which compares to the in vivo measurement (85 Nm). The average insertion forces for the press-fit cup varied from 5.2-6.8 kN (S1) and 7.2-11.5 kN (S2) ex vivo. Intraoperatively an average insertion force of 8.0 kN was determined. Conclusions: Implantation behaviour was influenced by acetabular cup design, bone substitute and experience of the surgeon. No specific density of bone substitute could be favoured for ex vivo investigations on the implantation behaviour of acetabular cups. The synthetic bone blocks of high density (31 pcf) led to problems regarding cup orientation and seating. Therefore, bone substitutes used should be critically scrutinized in terms of the comparability to the in vivo situation.

9

Evaluation of functional and structural changes affecting the lumbar spine in professional field hockey players

Ogurkowska M. B., Kawałek K.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 2

51--58

EN

Purpose: The aim of this study was to evaluate functional and structural changes in the lumbar spine. Methods: The research group consisted of 20 male professional field hockey players. Computed tomography scans were collected to define the radiological density of the vertebral bodies and to calculate Young’s modulus. An electrogoniometer was used to measure the range of movement. Geometric parameters, such as Lumbar Lordosis Angle, Index of Lumbar Lordosis, Whitmann-Ferguson Angle and Anterior Pelvic Tilt, were also measured. Results: The values describing lumbar lordosis increased linearly with years of training and were significantly greater than those reported in the literature. Field hockey players displayed a larger range of flexion, side bending and rotation to the right. An analysis of radiological density found significantly high values. An analysis of Young’s modulus showed that the vertebral bodies become more fragile. Conclusions: The results show that overuse changes in the lumbar spine of field hockey players are severe and highly correlated with years of training.

10

Formation of microcracks near surgical defect in femur : assessment of ultimate loading conditions

Bosiakov S. M., Alekseev D. V., Shpileuski I. E., Silberschmidt V. V., Stachowicz F., Trzepieciński T.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2016

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z. 88 [293], nr 2

91--99

EN

A bone defect of rectangular shape in a femur is considered as a result of a surgical resection of tumor lesions. Based on finite-element calculation of J-integral near the bone defect, ultimate combinations of loads corresponding to formation of microcracks were determined. The loads corresponds to simultaneous actions of own human’s weight, flexion-extension, adduction-abduction and rotation of the femur. Recommendations for the prevention of pathological fractures of the femur with the surgical defect based on the obtained results were formulated.

PL

W artykule przedstawiono wyniki badań w których analizowano wady kości udowej o prostokątnym kształcie będące wynikiem resekcji chirurgicznej zmian nowotworowych. Na podstawie obliczeń metodą elementów skończonych całki J w okolicy wady kości określono niszczące kombinacje obciążeń odpowiadające powstawaniu mikropęknięć. Obciążenia odpowiadające jednoczesnemu obciążeniu kości przez ciężar człowieka, obciążenia ściskająco-rozciągające, odwodzenie i obrót kości udowej. Na podstawie uzyskanych wyników sformułowano zalecenia dotyczące zapobiegania patologicznemu złamaniu kości udowej z defektem chirurgicznym.

11

Zastosowanie ultradźwięków w leczeniu uszkodzeń i odbudowie kości. przegląd piśmiennictwa

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

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2014

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Vol. 20, nr 3

172--180

PL

Terapia ultradźwiękowa jest obecnie szeroko dostępna oraz stosowana w fizjoterapii i medycynie sportowej. Pulsacyjne ultradźwięki niskiej częstotliwości LIPUS (ang. low-intesity pulsed ultrasound) nie powodują zmian termicznych. Badania kliniczne, zgodne z medycyną opartą na faktach, potwierdziły możliwość ich zastosowania w procesie zrostu kostnego. Celem pracy jest przegląd obecnego stanu wiedzy na temat LIPUS. Do badań wykorzystano platformę Web of Knowledge. Używanym językiem był język angielski. Jako opcje wyszukiwania zostały użyte różne kombinacje słów kluczowych: LIPUS, bone, soft tissue, healing. Wyszukiwania zostały zawężone do publikacji z ostatnich 10 lat z włączoną lematyzacją. 10 prac zostało ocenionych pod kątem skuteczności randomizacji dla potrzeb medycyny opartej na faktach. Badania, głównie przedkliniczne, dowodzą przydatności stosowania LIPUS w przypadku opóźnionego zrostu kostnego lub jego braku. Jednakże niska wartość metodologiczna badań nad zwierzętami bądź liniami komórkowymi sugeruje potrzebę dalszego kontynuowania prac.

EN

The ultrasound therapy is now widely available and used in physiotherapy and sports medicine. The low-intensity pulsed ultrasound (LIPUS) does not cause any thermal reactions. Clinical examination, conducted in accordance with the evidence-based medicine, has confirmed its applicability in the process of bone healing. The purpose of the review is to review the current state of knowledge on LIPUS. Web of Knowledge platform was exploited. The language used was English. Different combinations of keywords were used as the search options: LIPUS, bone, soft tissue, healing. The exploration was restricted to the publications from the last 10 years and included lemmatization. 10 papers were evaluated in terms of results efficacy of randomization for the evidence-based medicine purposes. The examination, mainly preclinical, proved the usefulness of LIPUS in the case of delayed union or non-union of bone. However, the low value of methodological studies on animals or cell lines suggests the need for further continuation of the work.

12

Method of Skeletal System Modelling

Olszewski H., Wojnicz W., Wittbrodt E.

Archive of Mechanical Engineering

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2013

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Vol. LX, nr 3

335--346

EN

An original method of skeletal system modelling is presented in detail. Using DICOM images obtained from CT and PET tests, shell models of nine bones were created (humerus, radius, ulna, scapula, clavicle, femur, tibia, fibula, pelvis). Two methods of bone behaviour are also proposed, the first method treating the bone as a solid structure and the second method treating the bone as a complex porous structure. The behaviour of model parts is numerically examined by using the finite element method.

PL

W artykule opisano autorską metodę modelowania układu szkieletowego. Stosując zdjęcia DICOM otrzymane z badania CT i PET, utworzono dziewięć modeli powłokowych kości (kości ramiennej, kości promieniowej, kości łokciowej, łopatki, obojczyka, kości udowej, kości piszczelowej, kości strzałkowej i miednicy). Zaproponowano dwie metody modelowania zachowania kości. Zgodnie z pierwsza metoda kość jest traktowana jako bryła jednorodna, zgodnie z druga metoda - jako złożona struktura porowata. Zachowanie składowych części modelu zostało numerycznie przebadane, stosując metodę elementów skończonych.

13

Zmiany własności mechanicznych kości zwierzęcych w zależności od stopnia nawilżenia preparatu

Sadowska J., Kromka-Szydek M.

Aktualne Problemy Biomechaniki

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2012

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z. 6

111--116

14

The meaning of the piezoelectric and streaming potential in bone remodeling

Lech Ł., Iwaniec M.

Vibrations in Physical Systems

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2010

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Vol. 24

251--258

EN

In this paper authors include the most important information about piezoelectric effect and streaming potential occurring in bone. In their opinion these phenomena play important role during bone remodeling, so that model binding them together was proposed. Model describes mechanisms responsible for “sensing” by osteocyteslocal changes in stresses and strains and for signal transmissions from sensors to effectors i.e. osteoblasts.

PL

W pracy tej zawarto najważniejsze informacje dotyczące występowania efektu piezoelektrycznego oraz potencjału przepływu w strukturach kostnych, które zdaniem autorów tego tekstu, ma odgrywa ważną rolę przy przebudowie tkanki kostnej. Dlatego został zaproponowany model odbierania sygnałów o stanie mechanicznym kości przez osteocyty i powiązany z modelem oddziaływań międzykomórkowych opisującym przekazywanie informacji z osteocytów do osteoblastów.

15

Identification of the elastodamping properties of long bones on a basis of the degenerate models

Panek M.

Vibrations in Physical Systems

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2010

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Vol. 24

313--318

EN

The dynamic load is essential for proper working of the skeletal system. The loads affecting skeleton during practising different kinds of sports and when accidents occur (for example resulting with bone injuries) have dynamic character, often with periodical or pulse shape. Therefore, from the scientific and clinical point of view, assignment of the dynamical properties of bone tissues is necessary. In this paper two degenerate models for description of the bovine bones dynamic properties are presented. The whole femur bone supported as a cantilever beam with additional masson the free end is subject of investigations. The excitation is applied by electro-dynamic shaker. The force sensor is situated between shaker and the bone, and the reaction of the system is measured by acceleration sensor. On the basis the energy balance and the power balance equations the models parameters are identified. In this paper is presented a set of parameters describing chosen models for two cases. In the first case, it is assumed that a value of the additional mass is not known, and in the second case calculations are performed for known value of the substitutional mass. In the first case for both models (built on a basis of the Zener model I and the system basing on the general model of viscoelastic body II), a majority of identified parameters are negative. For a given mass value, in model I every parameter had positive value whereas in model II only the damping parameter was negative. The obtained results indicate that the model I is more suitable to describe of the bone dynamical properties.

PL

Do prawidłowego funkcjonowania układu kostnego niezbędne jest działanie obciążeń o charakterze dynamicznym. Siły działające na kościec podczas uprawiania różnych rodzajów sportu oraz podczas wypadków, np. prowadzących do uszkodzenia kości, także mają charakter dynamiczny, w tym często o przebiegu impulsowym lub okresowym. Dlatego tez z naukowego oraz klinicznego punktu widzenia, istotne jest poznanie własności dynamicznych tkanek kostnych. W niniejszej pracy przedstawiono dwa modele zdegenerowane, mające opisać własności dynamiczne kości wołowych. Badaniom poddano całą kość udową, która mocowana była w układzie belki wspornikowej z dodatkową masą. Wymuszenie realizowane było za pomocą wzbudnika elektro-dynamicznego. Pomiędzy nim a kością umieszczony był czujnik siły, natomiast odpowiedź układu rejestrowana była za pomocą czujnika przyspieszenia. Na tej podstawie za pomocą metody bilansu energii i bilansu mocy identyfikowano wartości parametrów występujących w modelach. Ruch masy dodatkowej zamocowanej na wolnym końcu kości, rozpatrywano jako drgania masy w układzie o jednym stopniu swobody. W pracy przedstawiono zestaw parametrów opisujących wybrane modele dla dwóch przypadków. W pierwszym założono, że wielkość masy dodatkowej nie jest znana, a w drugim obliczenia przeprowadzono dla zadanej wielkości masy zastępczej. W pierwszym przypadku, zarówno układzie w bazującym na modelu Zenera I jak i powstałym na bazie ogólnego modelu ośrodka sprężysto-lepkiego II, większość identyfikowanych parametrów przyjmowała wartości ujemne. Przy zadanej wielkości masy, w modelu I wszystkie parametry przyjmowały wartości dodatnie, natomiast w modelu II tylko parametr tłumienia był ujemny. Na tej podstawie wydaje się, że model l Iepiej nadaje się do opisu właściwości dynamicznych kości.

16

FEM analysis of expandable intramedullary nails in healthy and osteoporotic femur

Kajzer W., Kajzer A., Marciniak J.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

563-570

EN

Purpose: The paper presents the results of numerical analysis of expandable intramedullary nail – femur system in different states of healing. The aim of the research was to determine displacements, deformations and stresses occurring in a bone depending on the age of the patient and the extent level of osteoporosis. Design/methodology/approach: A femur was selected to numerical analysis. The analysis concerned the influence of the load and torsion of the system on the obtained results of displacements, deformations and reduced stresses. In order to make calculations, four models with different mechanical properties were chosen: model 1: femur with mechanical properties corresponding with a femur of a patient at the age of 16, model 2: with mechanical properties corresponding with a femur of a patient at the age of about 28, model 3: with mechanical properties corresponding with a femur of a patient at the age of about 20 and at the age of 50 to 65 years old and model 4: with mechanical properties corresponding with a femur of a patient at the age above 70 or with osteoporosis. For the chosen model of intramedullary nail, mechanical properties of titan alloy Ti-6Al-4V were used. Two load steps were analyzed: load step 1 in which simple axial load with a value ranging from 250 up to 1000 N simulating patient standing on one leg was used, and load step 2 – a torsion analyzing loads that the nail is exposed to while walking. Findings: Conducted analysis of the system showed the difference in displacements, deformations and reduced stresses depending on assumed mechanical properties of femur and load step of the system. Research limitations/implications: The limitations were connected with the necessity of simplifying the assumptions, which were associated with limitations caused by boundary conditions. In researches 4 forces loading the femur axially were used: 1: force F = 250N, 2: with force F = 500N, 3: with force F= 750N and 4: with force F = 1000N and 5 values of angle displacement of the femur head were assumed: 1: angle displacement ö = 1°, 2: ö = 5°, 3: ö = 10°, 4: ö = 15°, 5: ö = 20°. Practical implications: Obtained results can be applied in selection of stabilization methods of bone fragments and in forecasting biomechanical conditions depending on the age of patient and the state of his general conditions of bones. Originality/value: The paper presents the displacement-deformation-stress characteristics of femur - expandable intramedullary nail system, using the Finite Elements Method (FEM) in the analysis.

17

Związki gęstości prześwietleniowej oraz zawartości składników mineralnych w ludzkiej kości beleczkowej z jej wytrzymałością

Mazurkiewicz A.

Acta Mechanica et Automatica

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2009

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Vol. 3, no. 3

39-42

PL

W pracy przedstawiono wyniki badań związków gęstości prześwietleniowej oraz zawartości składników mineralnych w ludzkiej kości beleczkowej z jej wytrzymałością. Dokonano oceny stopnia zgodności szacowania wytrzymałości kości na podstawie pomiaru gęstości prześwietleniowej kości, w porównaniu z szacowaniem wytrzymałości na podstawie zawartości składników mineralnych w kości.

EN

In the paper, it was presented results of investigation relations between DEXA density, mineral content and strength of human trabecular bone. An agreement of evaluation strength of trabecular bone on the base DEXA density and mineral content of trabecular bone was proved.

18

Możliwości obliczeniowej oceny wartości modułu Younga dla kości beleczkowej

Mazurkiewicz A., Topoliński T.

Acta Mechanica et Automatica

|

2009

|

Vol. 3, no. 3

43-46

PL

W pracy przedstawiono wyniki badań związków gęstości prześwietleniowej oraz zawartości składników mineralnych w ludzkiej kości beleczkowej z jej wytrzymałością. Dokonano oceny stopnia zgodności szacowania wytrzymałości kości na podstawie pomiaru gęstości prześwietleniowej kości, w porównaniu z szacowaniem wytrzymałości na podstawie zawartości składników mineralnych w kości.

19

Stresses present in bone surrounding dental implants in FEM model experiments

Żmudzki J., Walke W., Chladek W.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 27, nr 1

71-74

EN

Purpose: Appropriate selection of material and geometric characteristics of intraosseus pillar implant part creates a possibility to control the bone tissue loading. Design/methodology/approach: A basic tool that is commonly used the evaluation of bone loading state is the linear FEM analysis. It requires setting of appropriate experiment conditions. Hence, an analysis has been carried out in order to determine the influence of dividing method of finite elements (tetragonal type 187 in Ansys system v.11) on stresses in pillar and surrounding bone tissue. Findings: Seeking of loading values cortical bone tissue is highly affected by the increase of mesh density on the edge of implant insertion into the cortex bone. Loading stresses values have significantly increased along with increased mesh density, whereas the differences have even reach 47 MPa. Research limitations/implications: Research has been carried out only for the Ansys system in the linear range assuming standard shape and mechanical characteristics of implant and bone, as well as regarding the after the osseointegration phase because if the presumed complete adherence of the pillar to the bone. Practical implications: Excessive increase of mesh density leads to overestimation of loading stresses values and further to an unjustified increase of pillars' diameter. At the other hand, too large elements might lead, through an underestimation of loading stress level, to overloading atrophy of bone tissue. Originality/value: This paper points out the necessity of more determined activities aimed on defining appropriate and uniform FEM experiment conditions that would enable achievement of more real results of model researches and their comparability.

20

Badania dynamiki zastępczego układu kość-implant dla potrzeb diagnostyki medycznej

Nowak B., Kaczmarek M.

Diagnostyka

|

2008

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nr 1(45)

75-84

PL

W pracy przedstawiono studium połączenia zastępczego kości i implantu podjęte dla rozwijania metody diagnozowania stanu spójności na podstawie metod wibroakustycznych. Przeprowadzono symulacyjne badania numeryczne mające na celu identyfikację dynamicznych parametrów układu w postaci zbioru częstotliwości i postaci drgań własnych. Przedyskutowano zmiany parametrów dynamicznych układu w funkcji utraty spójności połączenia w ramach przyjętego modelu odspajania. Analiza teoretyczna została uzupełniona badaniami eksperymentalnymi.

EN

In this paper the study of substitute model of bone-implant system was presented created for the purpose of diagnosing of the state of integrity based on vibrational techniques. In the frame of work, dynamic parameters of the system were eshablished as a sets of eigenfrequencies and eigenvectors using numerical tools. The shifts of eigenferquecies in spectrum of the systems under consideration were discussed in the scope of loosenig integrity between bone and implant. Additionally, the research was augmented by experimental study.