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1

Body balance a few years after total hip replacement

Wareńczak Agnieszka, Lisiński Przemysław

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 1

87--96

EN

These aim of the study was to conduct a long-term evaluation of whether total hip replacement permanently affects the dynamic body balance. Methods: Twenty-five patients after the unilateral total hip replacement (mean age: 69.9 ± 6.2) and 25 subjects without the total hip replacement (mean age: 68.4 ± 4.8) who matched the age and overall health participated in this study. The force platform and functional tests such as Timed Up and Go, 3m walk test, Functional Reach Test, 30s Chair Stand Test, Step Test and Berg Balance Scale were used to assess dynamic balance. The results obtained in individual trials were compared using the Student’s t-test for independent variables, the Welch test or the non-parametric Mann–Whitney U-test. Results: Subjects from the THR group exhibited significantly increased time and distance in the tests performed on the force platform, compared to the control group. We also observed worse balance and functional test scores in the THR group: Timed Up and Go test ( p < 0.001), 3 m walk test ( p < 0.001), Functional Reach Test ( p < 0.001), 30 s Chair Stand Test ( p = 0.001) and Step Test (operated leg: p < 0.001, non-operated leg: p < 0.001). The results obtained in the Berg Balance Scale tests were not significantly different between the groups ( p = 0.218). Conclusions: We observed significant differences in postural stability and dynamic balance between patients after THR and subjects in the same age without endoprosthesis. Our research shows that total hip replacement permanently impairs patients’ dynamic balance and their functionality in certain lower-extremity activities.

2

Crack growth path simulation in a cement mantle of THR using crack box technique

Boulenouar Abdelkader, Bendida Nadjet

Journal of Theoretical and Applied Mechanics

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2019

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Vol. 57 nr 2

317--329

EN

A numerical method for 2D LEFM crack propagation simulation in a cement mantle of the total hip replacement (THR) is presented. This work is based on the implementation of the displacement correlation technique (DCT) and the maximum circumferential stress (MCS) theory in a finite element code, using the Ansys Parametric Design Language (APDL). At each crack increment length, the crack direction angle is evaluated as a function of stress intensity factors (SIFs). The crack box technique is investigated for crack propagation simulation. The advantage of this technique is facilitation of the automatic remeshing of the structure during crack extension. In this paper, we analyzed the mechanical behavior of cracks initiated in the cement mantle by evaluating the SIFs. The effect of the cavities and the initial crack directions on the crack growth path has been highlighted.

3

On the choice of thickness of the cement mantle in cemented hip arthroplasty

Levadnyi I., Awrejcewicz J., Loskutov A., Szymanowska O.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 4

1235--1244

EN

Recommendations for the optimal thickness of the cement mantle in cemented hip arthroplasty are outlined based on the results obtained with the finite element method. The investigations show that distal femur cement thickness higher than 2 mm positively affects mechanical behaviour of the cement mantle and can be useful in reducing stress-strain levels in the distal part of the femur what leads to prevention of development of a stress-shielding effect. The results of the study can contribute to the success of long-term implants.

4

Hip joint and hip endoprosthesis biomechanics

Gryka J.

Journal of Technology and Exploitation in Mechanical Engineering

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2017

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Vol. 3, nr 1

21--27

EN

This article contains a description of the basic issues related to anatomy, loading of hip joint and its endoprosthesis research methods. The methods of testing and simulating hip joint loads, factors that influence the selection of parameters during the design of prostheses, typical solutions to engineering problems related to this topic are presented. The article concludes with short summary of the finite element method for the design of hip replacements.

PL

Artykuł zawiera opis podstawowych zagadnień związanych z anatomią, obciążeniami i metodami badawczymi dotyczących stawu biodrowego oraz jego endoprotezy. Przedstawione są sposoby badania i symulowania obciążeń w stawie biodrowym, czynniki wpływające na dobieranie parametrów podczas projektowania endoprotezy oraz typowe rozwiązania problemów inżynierskich związanych z tym tematem. Artykuł zakończony jest krótkim streszczeniem zastosowań metody elementów skończonych podczas projektowania endoprotezy stawu biodrowego.

5

Zastosowanie spiekanych biomateriałów ze stali 316L na węzły tarcia endoprotez stawu biodrowego

Grądzka-Dahlka M., Dąbrowski J. R., Deptuła P.

Tribologia

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2010

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nr 1

19-26

PL

Wśród zagadnień biotribologii jednym z najczęściej pojawiających się problemów jest wydłużenie trwałości endoprotez stawów. Konieczność zapewnienia korzystnych parametrów tarciowych przy zachowaniu wymogów biozgodności implantów wymusza poszukiwanie nowych rozwiązań. W pracy przedstawiono koncepcję węzła tarciowego endoprotezy stawu biodrowego opartego na pracy samosmarnego łożyska porowatego. Panewka z warstwą porowatą, wykonaną z porowatego spieku ze stali 316L, powinna zapewnić niskie współczynniki tarcia i małe zużycie elementów współpracujących. Badania przeprowadzono na symulatorze tarcia stawu biodrowego. W celach porównawczych wykonano także analogiczne testy dla tradycyjnych panewek polietylenowych. Ocenę zużycia panewek przeprowadzono zgodnie z normą ISO 14242-2. Badania eksperymentalne potwierdziły słuszność koncepcji porowatego łożyska endoprotezy stawu biodrowego.

EN

One of the most common among the biotribological issues is elongation of joint endoprosthesis durability. Necessity to ensure favourable friction parameters along with the implants biocompatibility requirements forces search for new solutions. The new conception of tribological system of hip joint endoprosthese, based on the idea of porous selflubricating bearing, was presented in this work. Hip joint cup with porous layer made of porous sintered 316L steel should ensure low friction coefficient as well as low wear of working elements. Research were undertaken on hip joint friction simulator. Similar tests were taken for traditional polyethylene cup for comparison. Wear assessment were led in accordance with ISO 14242-2. Experimental research confirmed legitimacy of the conception of porous hip joint bearing.