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1

Artificial neural network simulation of lower limb joint angles in normal and impaired human gait

Błażkiewicz M., Wit A.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 3

43--49

EN

Simulating the complexities of lower limb motion can be useful for orthosis or rehabilitation planning. The aim of this study was to develop an artificial neural network (ANN) able to accurately simulate the changes in the angle of the ankle, knee and hip joints during the gait cycle, then to use it to simulate the impact of a restricted range of ankle and hip joint angle changes on the progression of the knee joint angle. Methods: Thirty four young healthy students participated in the study. Gait kinematics data were collected using the Vicon system, then analyzed with an ANN. Results: We developed an ANN able to accurately simulate the progression of joint angles of lower-limb motion; its simulation of the impact of restricted ankle and hip joint angular ranges in the on the knee joint indicate that the braking phase is critical. Conclusions: ANNs offer a useful research method in clinical biomechanics. Further research in this vein should expand our understanding of compensatory functions in the lower limbs.

2

Assessing the asymmetry of free gait in healthy young subjects

Kaczmarczyk K., Błażkiewicz M., Wit A., Wychowański M.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 3

101--106

EN

Purpose: The purpose of this study was to derive reference values for a four-level scale intended to evaluate variation in free gait asymmetry measurements in healthy subjects. Methods: This evaluation is based on kinetic values for the left and right lower limbs during gait, registered with advanced measurement systems and assessed using the symmetry index (SI) developed by Robinson. Results: For the majority of parameters, the SI does not follow normal distribution. As such, quartile values were used to create intervals for a four-step scale of assessing symmetry of free gait in healthy subjects for each studied gait parameter. The SI rating intervals were from 0% (very good symmetry) to 21.2% (very poor symmetry) for kinetic parameters. The poorest symmetry was observed for horizontal force F3. Conclusions: The four-step scale of assessing symmetry in free gait in healthy subjects can be used in diagnosing gait disorders, devising surgical treatment strategies, and monitoring the rehabilitation process. Reference values for intervals of symmetry indicators in healthy subjects can be used as criteria for comparing individuals with/without disabilities.

3

Symulacja sił mięśniowych kończyn dolnych podczas pchnięcia kulą

Łysoń B., Kwacz M., Błażkiewicz M., Wit A.

Aktualne Problemy Biomechaniki

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2015

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z. 9

73--78

PL

W pracy wyznaczono czasowe przebiegi sił mięśniowych kończyn dolnych za pomocą modelu matematycznego u sportowca wykonującego pchnięcie kulą. Szczegółowo przedstawiono proces generowania symulacji w programie OpenSim na podstawie danych pochodzących z systemu Vicon Nexus. Zdefiniowany model ukazał, które mięśnie generują największą siłę w trakcie wykonywania ruchu pchnięcia kulą oraz które mięśnie pracują w warunkach ekscentrycznych. Istnieje możliwość wykorzystania wygenerowanego modelu do dalszych symulacji mających na celu szczegółową analizę techniki wykonywania pchnięcia kulą.

EN

Time trajectories of muscle forces for an athlete performing the shot put were modeled in the following article. The process of generating simulation in OpeSim software based on Vicon Nexus system data was presented in detail. The generated model showed which muscles generate the highest force while performing the movement of the shot put. It was also presented which muscles are working in eccentric conditions, which may cause injury. There is a possibility to use the generated model for further simulations, in order to conduct detailed analysis of shot put technique.

4

Laterality versus jumping performance in men and women

Trzaskoma Z., Ilnicka L., Wiszomirska I., Wit A., Wychowański M.

Acta of Bioengineering and Biomechanics

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2015

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Vol. 17, no. 1

103--110

EN

Purpose: The aim of this study was to investigate relationships between functional asymmetry of lower limbs, taking into account morphological features of the feet, and jumping ability in men and women. Methods: The study population consisted of 56 subjects, 30 women (age: 20.29 ± 0.59 years; body mass: 58.13 ± 4.58 kg, body height: 165.60 ± 5.03 cm) and 26 men (age: 20.41 ± 0.78 years, body mass: 78.39 ± 8.42 kg, body height: 181.15 ± 6.52 cm). The measurements of longitudinal arches were performed with the plantographic method on the basis of Clarke’s angle mapped on a computer foot print. The measurements of jumping performance during bilateral (two legs) and unilateral (single-leg) counter movement jump (CMJ) were done on force plate. All subjects jumped three times each type of jump (total 9 jumps): three right leg, three left leg and three two legs. We put the test results through a detailed statistical analysis with the Statistica 8.0. The t-test for dependent variables and the Wilcoxon signed-rank test for divergent variances of the features compared. The analysis of relationships between the chosen podometric and plantographic features and jumping performance was conducted on the basis of the Pearson product-moment correlation coefficient (for the features which presented normal distribution, according to the Shapiro–Wilk test). Results: The correlations between values of height of single-leg jumps (right and left) and bilateral jumps, and foot indices were found in few cases only in men who had greater values of jump height with the non-dominant limb. We did not find a significant difference in jumping ability between the dominant limb and the non-dominant limb in women. We found bilateral deficits in jumping ability in the study groups, though we did not find significant differences (P ≤ 0.05) between the values for women (a mean of 6.5%) and for men (a mean of 8.4%). Conclusion: We found significant gender differences of the correlations between the values of height of jumps (single-leg and bilateral jumps) and foot indices.

5

Laterality versus ankle dorsiand plantarflexion maximal torques

Trzaskoma Z., Ilnicka L., Wiszomirska I., Wit A., Wychowański M.

Acta of Bioengineering and Biomechanics

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2015

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Vol. 17, no. 2

131--141

EN

Purpose: The aim of the study was to analyze the connections between the functional asymmetries of lower limbs, taking into account morphological feet features, and ankle dorsi- and plantarflexion maximal torques in men and women. Methods: The study population consisted of 56 young subjects among which there were 30 women and 26 men. The assessment of upper and lower limbs’ side dominance was performed on the basis of surveys, verified with simple motor tasks that resembled the actions characteristic of the upper and lower limbs. The measurements of body build, as well as foot build, were performed with the use of accepted instruments according to the anthropometry standards. The measurements of longitudinal foot arches were conducted using the pantographic method. Ankle dorsi- and plantarflexion maximal torque values were measured under static conditions. Results: We found a positive correlation between the functional dominance of lower limb and greater strength only for ankle plantarflexion maximal torque values in correct laterality variants in women and in only one variant in men. No correlation was found between foot morphological asymmetry and the ankle dorsiand plantarflexion maximal torque values, either in women or in men. Conclusion: Our results support the idea that the functional lower limb dominance is not equivalent to the greater muscle strength.

6

Comparison of four methods of calculating the symmetry of spatial-temporal parameters of gait

Błażkiewicz M., Wiszomirska I., Wit A.

Acta of Bioengineering and Biomechanics

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2014

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Vol. 16, no. 1

29--35

EN

Although gait symmetry is being evaluated and reported in the literature with increasing frequency, there is still no generally accepted standard for assessing symmetry, making it difficult to compare studies and establish criteria to guide clinical decision-making. The purpose of this study was to ascertain whether gait symmetry in healthy subjects is consistent when assessed using various coefficients (RI, SI, GA, and SA), and if possible to identify a gait symmetry coefficient with the highest diagnostic utility. The study involved a group of 58 healthy university-level students of physical education and secondary school students aged 20.03 ± 0.97. Measurements of spatial-temporal gait parameters were conducted using the ZEBRIS platform. Our analysis supports existing recommendations that the symmetry index (SI) should be used as the most sensitive assessment of gait symmetry on the basis of spatial-temporal parameters in healthy subjects. Moreover, we developed normative values of individual features for diagnostic purposes.

7

Wybrane problemy metrologiczne oceny morfologicznej i funkcjonalnej stopy w leczeniu palucha koślawego

Wychowański M., Nowiński K., Borucki B., Wit A., Adamczyk P., Laskowski J.

Pomiary Automatyka Kontrola

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2012

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R. 58, nr 1

48-51

PL

Paluch koślawy jest chorobą często występującą u kobiet. Wykonano RTG obu stóp w projekcji AP, bocznej i na palcach oraz MRI. Opracowano, trójwymiarowy model strukturalny szkieletu stopy. Przeanalizowano błędy wyznaczenia położeń poszczególnych znaczników. Zbadano równowagęu zdrowych osób metodą stabilograficzną. Pomiarów charakterystyk chodu dokonano na ścieżce podoskopowej. Względem młodszych kobiet przeprowadzono normowanie wyników starszych kobiet. Parametry charakteryzujące badane kobiety nie mają rozkładu normalnego. Profil chodu kobiet starszych opisano 19 parametrami. Różnice w chodzie obu badanych grup kobiet przejawiają się głównie w parametrach geometrycznych. Normy symetrii kobiet podano dla 1 kwartyla, mediany i 3 kwartyla.

EN

Hallux valgus is one of the most frequent forefoot disease in women. There was taken RTG of both feet in the AP, lateral and tip toe projection as well as MRI. A three-dimensional structural foot skeleton model was developed. There was analysed the uncertainty of landmark positioning together with the influence on foot geometric features. Balance mechanism was examined in healthy subjects using the HUR stabilographic platform. Gait characteristics were made on the pressure distribution plate produced by ZEBRIS. There were separated two groups of younger women and a group of older women. Normalization of older women was carried out in relation to the younger group. The parameters characterizing the investigated women did not have a normal distribution. The gait profile of older women is based on 19 parameters. Differences in gait performance of both groups of women are mainly manifested in the geometric parameters. The norms of the symmetry index for the women are given as 1 quartile, median and 3 quartile.

8

Comparison of sensitivity coefficients for joint angle trajectory between normal and pathological gait

Błażkiewicz M., Wit A

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 1

83-91

EN

Gait recordings exhibit intra-subject, inter-subject, within-trial and between-trial variability as well as data analysis methods. In medicine, comparison of different measuring method results or quantifying changes due to specific treatment is required. The aim of this study was to compare a group homogeneity with respect to dispersion around the reference curve and to compare waveforms of normal and pathological gait data based on joint angle curves. Data files were tracked using APAS system. Our own model of lower limb was used to calculate the trajectories of joint angles for 5 groups: healthy men, women, children, persons with drop foot and Trendelenburg's sign. Waveform parameterizations, RMS, IAE and correlation coefficients were used to compare joint angles with reference curve. The sample scores obtained in this work provide an important information about closeness in the shape of two curves. Using multiple techniques of data analysis will benefit and give more accurate information.

9

Use of artificial neural networks for assessing parameters of gait symmetry

Michalski R., Wit A., Gajewski J.

Acta of Bioengineering and Biomechanics

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2011

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Vol. 13, no. 4

65-70

EN

The study attempts to assess gait symmetry based on measurement of vertical component of ground reaction force (GRF) in lower limbs. The aim of the study was to compare the results of gait classification obtained by means of artificial neural networks (ANN) and authors' own quantitative index method. Twenty male and twenty female physiotherapy students participated in the study. Measurements were carried out by means of the Kistler force plate. The profiles of GRF were analysed using ANN which classifies the cases under one of four groups of asymmetry based on suitably prepared training set. Author's own index method was employed for quantitative assessment of the degree of gait asymmetry. The analysis of our symmetry index revealed that the difference between the cases classified by the network as symmetrical and other asymmetrical profiles was significant (p < 0.001), which suggests the conformity of both methods.

10

Wpływ zmiany położenia CoP na wartość błędu momentu siły w stawie skokowym w chodzie

Błażkiewicz M., Wit A.

Aktualne Problemy Biomechaniki

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2010

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z. 4

23--28

PL

Celem pracy jest przedstawienie analizy błędów oraz wyników symulacji wartości momentów sił w stawie skokowym dla płaskiego modelu kończyny dolnej, wynikających z różnego przebiegu środka parcia stopy na podłoże (CoP - center of pressure). Składowa przednio-tylna CoP była przesuwana o wektory [a;b], gdzie a i b - dowolne liczby rzeczywiste. Wartości uzyskane dla symulacji wskazują, że zmiana położenia CoP może generować bardzo duże błędy w wartościach momentów. Jak wynika z symulacji dla badanego modelu zmiana położenia CoP o wektor np. [0;7] cm, generuje krzywą tożsamą z trajektorią przebiegu momentów w stawie skokowym w chodzie charakterystycznym dla osoby niepełnosprawnej.

EN

The purpose of this study was to investigate the effect of errors in the center of pressure (CoP) locations on two dimensional lower limb joint moment during gait. Kinematics and kinetic data were synchronized in MatLab. Antero - posterior component of CoP was shifted by vectors [a;b], where a and b -real numbers. The study shows that change of the location of CoP can generate very large mistakes in calculation of joint moments. As results from simulation for studied model the change of CoP about the vector e.g. [0;7]cm, generate the curve the same like for the handicap person.

11

Strength of proximal humeral fraction fixation employing implants of various types - a study of porcine bones

Wychowański M., Obrębski M., Rąpala K., Wit A., Gajewski J., Marczak K.

Acta of Bioengineering and Biomechanics

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2008

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Vol. 10, nr 3

29-35

EN

In this study, the authors assess the strength of proximal humerus fracture fixation using different methods. The strength, while pulling out the chosen single Kirschner wires implanted in porcine bone, has been examined. Tests concerning the strength of fixation with different types of implants have been carried out on prepared models. We observed the maximum strength of the bone–single wire coupling for Kirschner wires of a 2.5 mm diameter with 100 mm thread where mean was 2396 N (SD 345). The mean strength of the 4 wires fracture fixation for Kirschner wires of a 2.5 mm diameter with 100 mm thread was 736 N (SD 229) and was similar to Kirschner wires of a 2.5 mm diameter with 10 mm thread where mean was 709 N (SD 191).