Ograniczanie wyników
Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 49

Liczba wyników na stronie
first rewind previous Strona / 3 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  knee joint
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 3 next fast forward last
EN
The paper presents results of preliminary research of vibroarthrography signals recorded from one healthy volunteer. The tests were carried out for the open and closed kinematic chain in the range of motion 90° – 0° – 90°. Analysis included initial signal filtration using the EMD algorithm. The aim was to investigate the occurrence of differences in the values of selected energy and statistical parameters for the cases studied.
EN
The paper presents results of preliminary research of analysis of signals recorded for open and closed kinematic chain in one volunteer with chondromalacia in both knees. The preliminary research was conducted in order to establish the accuracy of the proposed method and will be used for formulating further research areas. The aim of the paper is to show how FFT, recurrence plots and recurrence quantification analysis (RQA) can help in bioacoustic signals analysis.
EN
The aim of the paper was to analyse variables related to the force and fatigue of knee muscles in the right and left lower limbs among 17 male athletes. Methods: For both muscle groups, maximal isometric torque (Fmax) was determined with the use of Biodex System 4 Pro and the values of muscle fatigue index (FATI1–3) were calculated. Results: A significant difference was observed between the groups of short- and long-distance runners in the values of all fatigue indices of knee joint extensor muscles in the right limb. In turn, between the groups of athletes who had trained for 2–4 years or for 4.5–7 years and the group who had trained for 7.5–13 years, significant differences were observed in the values of all fatigue indices of knee joint flexor muscles in the right limb. The group training for 3–12 hours per week and the group training for 12.5–18.0 hours per week in the sports club differed significantly in the value of the maximal isometric torque of knee joint flexor muscles in the right limb and in the values of some fatigue indices (FAT1, FAT3) for knee joint flexor muscles in the right limb. The study reported numerous positive correlations between the assumed characteristics and the investigated variables of knee joint extensor and flexor muscles in the right and left lower limbs. Conclusions: Athletes present certain changes in variable values and positive correlations between some characteristics and investigated variables of selected knee muscles.
4
EN
The aim of the work was to show that the fatigue load of bone tissue causes permanent structural changes in it. Methods: On the basis of the movie recording of gait, the time courses of angular changes in the joints of the lower limb were determined. Using the method of transforming Denavit–Hartenberg coordinate systems, the course of force loading the hip joint and, after that, the course of normal contact reaction of the femoral head of the knee joint during gait for the support phase were determined. On the basis of the Hertz formula, the course of contact stresses in the femoral joint head and the damage coefficient were determined according to the Palmgren–Miner damage accumulation hypothesis. Results: A calculation example was made using own software. The course of the obtained damage factor was compared to the image fixed in the X-ray image after its appropriate processing. The thesis of the work has been confirmed to a satisfactory degree. Conclusions: The nature of the lesions is similar to the image of structural changes in the head of the joint. It should be assumed that the image fixed in the bone is the result of the stored history of loads. Analysis of the obtained image can be used to determine the state of bone strength.
5
Content available remote Use of motion capture in assisted of knee ligament injury diagnosis
EN
This study treats of the use of motion capture systems as the help diagnose knee injuries. It consists of the theoretical work and the application. The written work describes a course of research includes choice of research group, selection of appropriate exercises, find useful computational methods, description created for research applications and summary results. The practical part was to create an application for physiotherapists which could help them to diagnosis potential pathology of the knee. The purpose of this study was to test whether a motion capture system dedicated to entertainment can be used in the medical aspect. This system was test for selected methods and determined to be suitable for supporting the diagnosis of knee injuries. Otherwise it has to be written what was the reason of failure. The results of the study were that after trial and error methods peeled action and created application proved helpful.
PL
Wstęp: Staw kolanowy to największy staw w ludzkim ciele poddany różnym obciążeniom powiązanym z uprawianiem sportu i wykonywaniem zawodu. W obrębie tego stawu często dochodzi do urazów, które nie zostają w odpowiednio szybkim czasie zdiagnozowane. Metodą, z wyboru, mającą zastosowanie w obrazowaniu patologii stawu kolanowego jest badanie rezonansu magnetycznego (MRI). Celem pracy jest ocena skuteczności, znaczenia i przydatności sekwencji MR wykorzystywanych w ocenie patologii stawu kolanowego. Materiał i metody: Wyniki zebrano i opracowano na podstawie uzyskanych obrazów rezonansu magnetycznego w grupie pacjentów z urazem stawu kolanowego. Badano grupę liczącą 60 osób z podziałem na płeć, wiek, patologie i wskazanie kliniczne. Badania wykonano aparatem rezonansu magnetycznego Magnetom Essenza 1,5 T (Siemens, Niemcy), używając sekwencji koniecznych do oceny stawu kolanowego: T1-, T2-, PD-zależnych oraz sekwencji PD-zależnej połączonej z techniką saturacji tłuszczu (FAT SAT). Wyniki: Wszystkie sekwencje były jednakowo skuteczne w ocenie złamania rzepki. Wszystkie za wyjątkiem sekwencji T1-zależnej były jednakowo skuteczne w wykrywaniu torbieli Bakera i patologicznego płynu, a za wyjątkiem sekwencji T2-zależnej w wykrywaniu zwapnień. W ocenie patologii w zakresie więzadeł, łąkotki, chrząstki stawowej oraz występowania obrzęku tkanek miękkich i stanów zapalnych najskuteczniejsze okazały się sekwencja PD- i PD-zależna z FAT SAT. Wnioski: W ocenie patologii w zakresie stawu kolanowego za pomocą MR najskuteczniejsze okazały się sekwencje PD-zależna bez i z saturacją tłuszczu.
EN
Introduction: The knee joint is the largest joint in the human body subjected to various strains associated with practicing sports and exercising the profession. Injuries often occur within this knee joint, which are not diagnosed at the appropriate time. The method of choice applicable in the imaging of knee joint pathology is a magnetic resonance imaging (MRI). The aim of the work is to show the effectiveness of meaning and usefulness of the sequences, used in the assessment of pathologies of the knee joint. Material and methods: The results were collected and elaborated on the basis of obtained magnetic resonance images in the group of patients with a knee joint injury. A group of 60 subjects were examined with division into sex, pathologies, age and clinical indication. The examinations were carried out by a magnetic resonance apparatus Magnetom Essenza 1,5 T (Siemens Germany) using necessary sequences to estimate knee joint: T1-, T2- and dependent PD and dependent PD sequence combined with fat saturation technique (FAT SAT). Results: All sequences were equally effective in the assessment of patella fracture. All sequences with the exception of the dependent T1 sequence were equally effective in detecting the Baker cyst and the pathological fluid, with the exception of the dependent T2 sequence in the detection of calcifications. In the assessment of knee joint pathology in the scope of ligaments, meniscus, articular cartilage, and the occurrence of soft tissue edema and inflammation, the most effective sequence turned out to be PD- and PD with FAT SAT. Conclusions: In the assessment of knee joint pathology by means of (MRI) the most effective sequence turned out to be dependent PD without and with fat saturation (FAT SAT).
EN
The article discusses motion of a healthy knee joint in the sagittal plane and motion of an injured knee joint supported by an active orthosis. A kinematic scheme of a mechanism for the simulation of a knee joint motion is developed and motion of healthy and injured knee joints are modelled in Matlab. Angles between links, which simulate the femur and tibia are controlled by Simulink block of Model predictive control (MPC). The results of simulation have been compared with several samples of real motion of the human knee joint obtained from motion capture systems. On the basis of these analyses and also of the analysis of the forces in human lower limbs created at motion, an active smart orthosis is developed. The orthosis design was optimized to achieve an energy saving system with sufficient anatomy, necessary reliability, easy exploitation and low cost. With the orthosis it is possible to unload the knee joint, and also partially or fully compensate muscle forces required for the bending of the lower limb.
8
Content available Design Resistance of Welded Knees in Steel Frames
EN
The paper presents issues related to calculations of welded knee joints, in which the interconnected load-bearing elements, beams and columns, can be made from plate girders with slender webs. At the beginning, a typical knee joint of portal steel frame was characterized, along with presentation of calculations for the internal forces in characteristic zones of the knee, i.e. in tension, shear, and compression zone. Then, the checking procedures of resistance were presented in detail for each designated knee zone, paying particular attention to the influence of complex stresses state and loss of stability in the shear and the compression part of knee joint. The work also presents a comprehensive calculation example, which illustrates the described method usage in practical design of welded knees of steel frames.
EN
An increase in the value of the hamstring-to-quadriceps (H/Q) ratio with an increase in angular velocity may effectively prevent injuries of the back of the thigh. Previous studies have found that the conventional H/Q ratio was unaltered along with an increasing angular velocity in females. Therefore, this study aimed to investigate the relationships between the conventional H/Q ratio and angular velocity in a group of female soccer players. Methods: The study was carried out on a group of 16 female soccer players (age: 20.7 ± 3.9 years, body height: 166.1 ± 5.8 cm, body mass: 58.4 ± 6.2 kg, training experience: 8.8 ± 4.1 years). Measurements of peak torque of extensors and flexors of the knee joint under static conditions and under isokinetic conditions (at angular velocities of 30°/s, 60°/s, 90°/s and 120°/s) were carried out using a Biodex dynamometer. Results: There was a statistically significant increase in the conventional H/Q ratio with an increase in angular velocity. These differences occurred between measurements at angular velocities of 0°/s and 30°/s, and 30°/s and 60°/s. Conclusions: As previously found for males, an increase in conventional H/Q ratio with increased angular velocity was also present in this group of female players. This phenomenon should reduce the number of injuries of the muscles of back of the thigh. Coaches should pay attention to increasing the level of strength in the group of knee joint flexor muscles so as to make the value of the H/Q ratio appropriately high and increasing with increasing angular velocity.
EN
The observational study evaluated isokinetic parameters in patients at eight months after anterior cruciate ligament reconstruction (ACLR) utilizing semitendinosus and gracilis tendons autograft, with two different modes of physiotherapy, and investigated whether analysed parameters were affected by the postoperative physiotherapy supervision duration. Methods: Strict exclusion criteria were employed on a group of 259 ACL-reconstructed patients to identify two groups of males preoperatively well trained and frequently participating in sports, with different durations of postoperative physiotherapy supervision: Group I (n = 18; x = 27.67 weeks) and Group II (n = 20; x = 10.75 weeks). The patients underwent knee extensor and flexor muscles torques measurements with the 180°/s and 60°/s. The torque, position and time parameters were analysed. Limb Symmetry Index (LSI) was calculated. The parametric tests for dependent samples, parametric tests for independent samples, and linear Pearson’s correlation coefficient calculations were performed. Results: There were significant between-limb differences in the Group II in the knee extensor and flexor muscles torque parameters, with LSI ranging from x = 75.72 to x = 78.75 and from x = 78.69 to x = 87.82, respectively. The knee extensor muscles torque parameters and LSI values were positively correlated with the physiotherapy supervision duration. The inter-limb differences in the Group I and II in knee flexor muscles PT angle amounted to x = 10.94° (180°/s), x = 9.39° (60°/s), and x = 12.00° (180°/s), x = 9.75° (60°/s), respectively. Conclusions: The longer postoperative physiotherapy supervision was more effective for improving knee muscles torque parameters. The knee flexor muscles PT angle was shifted towards extension in the ACL-reconstructed limb, regardless of the time of postoperative physiotherapy supervision duration.
11
Content available Microscopic tribological analysis of the knee joint
EN
The aim of the conducted research was the evaluation of the topography and the structure of the superficial layer of meniscus and articular cartilage. These are surfaces that optimise the friction and lubrication process in the knee joint. The animal samples of the menisci and the articular cartilage were examined. The research was performed using scanning electron microscopes and an atomic force microscope. The structure of the surface of meniscus and articular cartilage is very regular. The collagenous fibres, which are embedded in the ground substance, are parallel to the surface. The undulation of the surface was observed. In the area of the anterior horn on tibia side of both menisci as well as in the anterior area of tibial plateau, the concavity and convexity pattern is evident. The observed cavities enable the accumulation of the synovial fluid. The synovial fluid plays the role of the lubricant in the knee joint, and its presence is highly desired during the load transmission.
PL
Celem przeprowadzonych badań była ocena topografii i struktury łąkotek oraz powierzchni stawowych, które zabezpieczają i optymalizują proces tarcia i smarowania w stawie kolanowym. Materiałem badań były łąkotki pobrane z prawidłowych stawów zwierzęcych oraz tkanka chrzęstna wypreparowana z powierzchni stawowych. Badania były realizowane na mikroskopach skaningowych oraz mikroskopie sił atomowych. Struktura warstwy wierzchniej chrząstki włóknistej oraz szklistej wykazała dużą regularność. Włókna kolagenowe biegnące równolegle do powierzchni i zatopione w substancji podstawnej tworzą łagodnie pofalowaną strukturę. Układ wgłębień i wzniesień jest najbardziej wyraźny na części przedniej plateau kości piszczelowej oraz w obszarze rogu przedniego łąkotek, po stronie kontaktującej się z plateau kości piszczelowej. W zaobserwowanych wgłębieniach może gromadzić się ciecz synowialna, która pełni rolę środka smarnego, i której obecność jest wysoce pożądana podczas przenoszenia obciążeń wewnątrz stawu kolanowego.
EN
Menisci are tissues that enable mobility and absorb excess loads on the knee. Problems in meniscus can trigger the disorder of osteoarthritis (OA). OA is one of the most common causes of disability, especially among young athlethes and elderly people. Therefore, the early diagnosis and treatment of abnormalities that occur in the meniscus are of significant importance. This study proposes a new computer-based and fully automated approach to support radiologists by: (i) the segmentation of medial menisci, (ii) enabling early diagnosis and treatment, and (iii) reducing the errors caused by MR intra-reader variability. In this study, 88 different MR images provided by the Osteoarthritis Initiative (OAI) are used. The histogram of oriented gradients (HOG) and local binary patterns (LBP) methods are used for feature extraction from these MR images along with the extreme learning machine (ELM) and random forests (RF) methods which are used for model learning (regression). As the first step of the pipeline, the most compact rectangular patches bounding the menisci are located. After this, meniscus boundaries are revealed by the morphological processes. Then, the similarities between these boundaries and the ground truth images are measured and compared with each other. The highest score is acquired with Dice similarity measurement with a success rate of 82%. A successful segmentation is performed on the diseased knee MR images. The proposed approach can be implemented as a decision support system for radiologists, while the segmented menisci can be used in classification of meniscal tear in future studies.
PL
W pracy określono wartości wybranych wskaźników ekscentrycznej siły mięśni uda siatkarzy w warunkach izokinetycznych. Ocenie poddano stosunek momentu siły hamstrings do quadriceps (H/Q) oraz bilateralny deficyt maksymalnego momentu siły mięśni (BD) dla prędkości kątowych 30°/s, 60°/s i 90°/s. Wartości maksymalnego H/Q zawierały się od 69.0% (90°/s) do 81.3% (30°/s), natomiast średniego H/Q od 68.6% (90°/s) do 78.7% (30°/s). Ponadto, stwierdzono nieistotny BD (poniżej 7%) dla obu zespołów mięśniowych.
EN
In the study the values of selected indicators of thigh eccentric isokinetic strength in volleyball athletes at angular velocities 30°/s, 60°/s and 90°/s was determined. The evaluation included the hamstrings to quadriceps torque ratio (H/Q) and peak torque bilateral deficit (BD). The peak H/Q values ranged from 69.0% (90°/s) to 81.3% (30°/s), whereas average H/Q values ranged from 68.6% (90°/s) to 78.7% (30°/s). Moreover, no significant BD values (less than 7%) were found for both muscle groups.
EN
The paper presents a geometrical modeling process of custom-designed plates stabilizing knee joint fractures (especially of a tibia). The pre-operational planning of the surgery for the exact surgical case was based on the bone models obtained from computed tomography (CT). The type the fractures was specified by the AO classification. The subsequent procedures of modeling were worked out by means of The following programs: Mimics (geometry reconstruction), Geomagic (modeling) and SolidWorks (designing and using for the analysis of the state of stresses under the influence of the forces affecting a tibia), Furthermore, with the use of the finite elements method, the correctness verification of the designed stabilizers was made taking into consideration the stresses. As a frame of reference for the results of this analysis a standard bone plate, which is applied in this type of fractures, was used.
PL
W pracy przedstawiono proces modelowania geometrycznego płytek stabilizujących złamanie kości stawu kolanowego (w szczególności kości piszczelowej). Na podstawie modeli kości uzyskanych w wyniku badania tomografem komputerowym możliwe było przedoperacyjne planowanie zabiegu dla konkretnego przypadku chirurgicznego. Charakter złamań określany byt w oparciu o klasyfikację AO. Opracowano kolejne etapy postępowania w procesie modelowania za pomocą programów Mimics (obrazowanie), Geomagic (modelowanie) oraz SolidWorks (projektowanie oraz analiza stanu naprężeń pod wpływem sil działających na kość piszczelową). Ponadto została wykonana weryfikacja poprawności zaprojektowanych stabilizatorów z uwagi na naprężenia przy użyciu metody elementów skończonych. Układem odniesienia do analizy wyników była standardowa płytka kostna używana w tego typu złamaniach.
EN
The paper is focused on designing a novel controllable and adjustable mechanism for reproducing human knee joint’s complex motion by taking into account the flexion/extension movement in the sagittal plane, in combination with roll and slide. Main requirements for a knee rehabilitation supporting device are specified by researching the knee’s anatomy and already existing mechanisms. A three degree of freedom (3 DOF) system (four-bar like linkage with controlled variable lengths of rockers) is synthesised to perform the reference path of instantaneous centre of rotation (ICR). Finally, a preliminary design of the adaptive mechanism is elaborated and a numerical model is built in Adams. Numerical results are derived from simulations that are presented to evaluate the accuracy of the reproduced movement and the mechanism’s capabilities.
EN
The paper presents results of the preliminary structural analysis of model of the endoprosthesis of the knee joint. Basics of anatomy and biomechanics of the knee joint were introduced. Based on data from computed tomography, the model of knee joint was constructed. The prototype of the endoprosthesis of the knee joint was designed. After determining physical properties of structural materials, the Finite Elements Analysis of the model was conducted under various load conditions. Finally the results of analysis are presented.
PL
Wstęp i cele: W pracy pokazano modelowanie analityczno-numeryczne równowagi sił działających w stawie kolanowym człowieka. W modelu numerycznym wykorzystano do obliczeń program numeryczny MS-Excel. Materiał i metody: W pracy wykorzystano podstawy teoretyczne z literatury biomedycznej. Zastosowano metodę modelowania analitycznego, analizę numeryczną oraz interpretację graficzną w programie MS-Excel otrzymanych wyników. Wyniki: W modelu teoretycznym wyprowadzono wzory analityczne opisujące wartości sił równoważących staw kolanowy. Model numeryczny przedstawia symulację wartości sił i obciążeń w stawie kolanowym dla przyjętych realnych danych liczbowych. Wnioski: Wartości sił równoważących staw kolanowy są kilkukrotne większe niż wartości działających obciążeń. Znajomość wartości obciążeń i sił równoważących staw kolanowy ma istotne znaczenie w praktyce ortopedycznej, rehabilitacyjnej, rekreacyjnej i sportowej.
EN
Introduction and aims: Some analytical and numerical modelling of load-balancing forces which act in the human knee joint has been described in this paper. In the numerical calculations have been used MS-Excel program. Material and methods: In this paper has been presented some theoretical basis which refer to biomedical literature. The method of analytical modeling, numerical analysis and interpretation of graphics results in MS-Excel program have been used in the considerations. Results: The theoretical model shows the determined analytical formulas describing the values of balancing forces in the knee joint. Numerical model simulates the values of forces and loads in the knee joint for the assumed real data. Conclusions: The values of load-balancing forces are a few times greater then the values of acting loads. Knowledge of some values for the load-balancing forces of the knee joint has essential meaning in the orthopedic, rehabilitation, recreation and sport practice.
EN
Position and displacement analysis of a spherical model of a human knee joint using the vector method was presented. Sensitivity analysis and parameter estimation were performed using the evolutionary algorithm method. Computer simulations for the mechanism with estimated parameters proved the effectiveness of the prepared software. The method itself can be useful when solving problems concerning the displacement and loads analysis in the knee joint.
EN
Position and displacement analysis of a spherical model of a human knee joint using the vector method was presented. Sensitivity analysis and parameter estimation were performed using the evolutionary algorithm method. Computer simulations for the mechanism with estimated parameters proved the effectiveness of the prepared software. The method itself can be useful when solving problems concerning the displacement and loads analysis in the knee joint.
PL
Celem była identyfikacja kształtu i położenia struktur stawu kolanowego obrazowanego rezonansem magnetycznym (MR) w stabilizowanej pozycji, w aspekcie rozkładu grubości chrząstki stawowej. Badano prawidłowe stawy kolanowe. Obrazowanie przeprowadzono przy wykorzystaniu aparatu MR typu otwartego ze stabilizatorem kąta zgięcia kolana w przekrojach strzałkowych, czołowych i horyzontalnych, w wybranych pozycjach kątowych. Pomiary chrząstki budującej powierzchnie stawowe stawu kolanowego wykazały znaczne zróżnicowanie jej grubości oraz pofalowania z charakterystycznym przesunięciem fali.
EN
The aim of the study was to use the MRI to identify the shape and position of the structures of knee joints in a stabilized position, in terms of the analysis of joint cartilage thickness on femoral condyles, tibia condyles and the patella. There were studied normal knee joints. Imaging was performed with use of an open-type gradient coil MR apparatus with a knee bending angle stabilizer. The research strategy consisted of imaging: sagittal sections in a fixed position of the femoral bone relative to tibia, in selected sagittal sections for stabilized position of the femur relative to tibia for angles ranged from -10 degrees to 50 degrees, at 5 degree intervals, in the frontal sections with physiological extension, in the horizontal sections with physiological extension. Based on the MR imaging, there was measured the distribution of the thickness of joint cartilage that covered the femoral condyles, condyles of tibia and patella. The measurements of the cartilage building the surfaces of the knee joint showed significant variation in its thickness and folds with a characteristic wavelength shift in the tested sections. Variable thickness and uneven structures can substantially affect the conditions of joint lubrication and transfer of the locomotive load. Introduction of the stabilized position of the femur relative to tibia to the MR imaging allows useful identification of particular cartilage layers that work together.
first rewind previous Strona / 3 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.