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1.
Zhongguo Gu Shang ; 33(8): 761-5, 2020 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-32875769

RESUMO

OBJECTIVE: To explore the tensile mechanics and anatomical characteristics of the posterior hip capsule, and provide biomechanical and anatomical evidence for capsule repair in total hip replacement. METHODS: Six bone-capsule-bone specimens were obtained from posterior hip joint of fresh frozen cadavers. The maximum strain, load, elastic modulus and load strain curves of the capsule ligament complex specimens were recorded by Instron Universal Material Testing Machine. Twelve cadaveric hip specimens were dissected to the capsule. The tensile strain of normal capsule and conventionally reconstructed capsule at 90 degrees of hip flexion were documented. The suture area of the posterior capsule was divided into nine sections, and the thicknessof different sections was measured and compared. Posterior capsule of the cadavers was repaired in conventionally way and anatomical way separately and simulated rehabilitation was conducted. The effect of rehabilitation on the repaired capsule was observed. RESULTS: The load-strain curve of capsule ligament complex conforms to rheological and viscoelastic characteristics. The maximum tensile strain of the complex was (39.21±5.23)%, the maximum load was (142.06± 34.15) N, the tensile strength was (1.65±0.38) MPa, and the elastic modulus is (14.23±5.62) MPa. At 90 ° hip flexion, the tensile strain of repaired capsule was higher than that of normal capsule, and the difference was statistically significant (P< 0.05). Tensile strain of conventionally reconstructed capsule is:upper part (37.0±4.9)%, middle part ( 53.3±1.1)%, lower part (68.3±6.2)%, tensile strain of normal capsule is:upper part (17.0±2.6)%, middle part (24.1±1.4)%, lower part (26.0± 4.3)% . The thickness of the posterior joint capsulein different sections is statistically significant (P<0.05), and capsule at 0.5cm proximal to the femoral insertion is suitable for suture. There the average thickness of capsule is:upper part (3.48 ± 0.11) mm, middle part (2.36 ± 0.09) mm, lower part (1. 59±0.24) mm. The posterior inferior joint capsule is thinnest at (1.42± 0.02) cm proximal to the femoral insertion, and sutures should be avoided here. After simulating rehabilitation, avulsion occurred in the lower part of the posterior capsule repaired conventionally (10/12), and the anatomically repaired capsule remained intact. CONCLUSION: The lower part of conventionally repaired capsule is overstretched and tends to fail. Anatomically repaired capsule conforms to tensile mechanics and is helpful to reduce the failure rate of repair.


Assuntos
Artroplastia de Quadril , Fenômenos Biomecânicos , Fêmur , Articulação do Quadril/cirurgia , Humanos , Cápsula Articular/cirurgia , Resistência à Tração
2.
Zhongguo Gu Shang ; 33(8): 766-70, 2020 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-32875770

RESUMO

OBJECTIVE: To establish a 3D finite element model of normal knee joint involved its meniscus, which can be used to simulate the anatomical morphology and characteristics of human knee joint, to verify the validity of the model by preliminary FEA mechanical analysis, and explain partially biomechanical mechanisms of meniscus. METHODS: CT and MRI data were harvested by scanning the knee joint of a healthy male volunteer, and then these data were imported into Mimics 10.01 software and Geomagic Studio software to constructed the 3D models of tissue structures of knee joint. These models were combined to constructed the 3D model of intact knee joint and meshed in ANSA software. Therefore the finite element model of intact knee joint was established. Finally, after the definitionof its material behavior, boundary conditions and loading. The finite element model of knee joint was analyzed and verified using ANSYS software. Meanwhile The biomechanical properties of meniscus were analyzed. RESULTS: The complete knee finite element model composed of bone, meniscus, articular cartilage, and major ligaments was established. It could effectively simulate the anatomical morphology and characteristics of knee joint and its meniscus. The contact area of medial meniscus was 771.05 mm2, while the contact area of lateral meniscus was 634.31 mm2, and the ratio was 1.216. The stress distribution was uniform, but the stress of the medial meniscus was higher than that of the lateral meniscus, and the peak stress located in the posterior horn of the medial meniscus and the anterior horn of the lateral meniscus, respectively, and the peak stress value was 4.11 MPa. The maximum displacement of the meniscus was located in body, and the displacement of the medial meniscus was more remarkable than that of the lateral meniscus, and the maximum displacement value is 0.33 mm. The obtained finite element analysis results corresponded to that reported in the literature, which mean the model's reliability. CONCLUSION: The established finite element model of knee joint are proved to be have validity, and is a useful model for finite element analysis of meniscus tear and menisectomy. The results of finite element analysis can explain partially biomechanical mechanisms of meniscus which can provide theoretical guidance for clinical treatment of meniscus injury.


Assuntos
Menisco , Fenômenos Biomecânicos , Análise de Elementos Finitos , Humanos , Articulação do Joelho , Masculino , Meniscos Tibiais , Reprodutibilidade dos Testes , Estresse Mecânico
3.
Nan Fang Yi Ke Da Xue Xue Bao ; 40(6): 911-915, 2020 Jun 30.
Artigo em Chinês | MEDLINE | ID: mdl-32895206

RESUMO

OBJECTIVE: To analyze the biomechanics of cystic lesions in the mandibular body in a three-dimensional (3D) finite element model. METHODS: A 3D finite element model of cystic lesion of the mandibular body was constructed based on the CT images of the mandible of a healthy adult female volunteer with normal occlusion. The size of the cyst and the residual bone wall were analyzed when the lesion area approached the stress peak under certain constraints and loading conditions. RESULTS: When the size of the cyst reached 37.63 mm×11.32 mm×21.45 mm, the maximal von Mises stress in the lesion area reached 77.295 MPa, close to the yield strength of the mandible with a risk of pathological fracture. At this point, the remaining bone thickness of the buccal and lingual sides and the lower margin of the mandible in the lesion area was 1.52 mm, 0.76 mm and 1.04 mm, respectively. CONCLUSIONS: Residual bone mass is an important factor to affect the risk of pathological fracture after curettage of cystic lesions. A thickness as low as 1 mm of the residual bone cortex in the cystic lesion area of the mandibular body can be used as the threshold for a clinical decision on one-stage windowing decompression combined with two- stage curettage.


Assuntos
Imageamento Tridimensional , Mandíbula , Adulto , Fenômenos Biomecânicos , Feminino , Análise de Elementos Finitos , Humanos , Estresse Mecânico
4.
Arthroscopy ; 36(9): 2510-2512, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32891251

RESUMO

The medial patellofemoral complex, composed predominantly of the medial patellofemoral ligament, plays an important role in patellar tracking and stability. Medial patellofemoral ligament reconstruction is accordingly one of the most broadly applied surgical techniques for treating patellar instability. Orthopaedic research has demonstrated that surgeries that restore native anatomy are often more effective. The medial patellotibial ligament clearly serves an important supporting role in patellar tracking and stability, particularly in early flexion, and its inclusion in medial soft-tissue reconstructions more closely restores native patella tracking. Whether reconstructions incorporating the medial patellotibial ligament will translate to improved outcomes remains unclear.


Assuntos
Luxação Patelar , Articulação Patelofemoral , Fenômenos Biomecânicos , Humanos , Ligamentos Articulares , Patela
5.
Nat Commun ; 11(1): 3805, 2020 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-32732886

RESUMO

The study of organoids, artificially grown cell aggregates with the functionality and small-scale anatomy of real organs, is one of the most active areas of research in biology and biophysics, yet the basic physical origins of their different morphologies remain poorly understood. Here, we propose a mechanistic theory of epithelial shells which resemble small-organoid morphologies. Using a 3D surface tension-based vertex model, we reproduce the characteristic shapes from branched and budded to invaginated structures. We find that the formation of branched morphologies relies strongly on junctional activity, enabling temporary aggregations of topological defects in cell packing. To elucidate our numerical results, we develop an effective elasticity theory, which allows one to estimate the apico-basal polarity from the tissue-scale modulation of cell height. Our work provides a generic interpretation of the observed epithelial shell morphologies, highlighting the role of physical factors such as differential surface tension, cell rearrangements, and tissue growth.


Assuntos
Forma Celular/fisiologia , Células Epiteliais/citologia , Organoides/citologia , Organoides/crescimento & desenvolvimento , Animais , Fenômenos Biomecânicos , Proliferação de Células/fisiologia , Simulação por Computador , Modelos Biológicos , Tensão Superficial
6.
PLoS Comput Biol ; 16(8): e1007961, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32810174

RESUMO

Tumour spheroids are widely used as an in vitro assay for characterising the dynamics and response to treatment of different cancer cell lines. Their popularity is largely due to the reproducible manner in which spheroids grow: the diffusion of nutrients and oxygen from the surrounding culture medium, and their consumption by tumour cells, causes proliferation to be localised at the spheroid boundary. As the spheroid grows, cells at the spheroid centre may become hypoxic and die, forming a necrotic core. The pressure created by the localisation of tumour cell proliferation and death generates an cellular flow of tumour cells from the spheroid rim towards its core. Experiments by Dorie et al. showed that this flow causes inert microspheres to infiltrate into tumour spheroids via advection from the spheroid surface, by adding microbeads to the surface of tumour spheroids and observing the distribution over time. We use an off-lattice hybrid agent-based model to re-assess these experiments and establish the extent to which the spatio-temporal data generated by microspheres can be used to infer kinetic parameters associated with the tumour spheroids that they infiltrate. Variation in these parameters, such as the rate of tumour cell proliferation or sensitivity to hypoxia, can produce spheroids with similar bulk growth dynamics but differing internal compositions (the proportion of the tumour which is proliferating, hypoxic/quiescent and necrotic/nutrient-deficient). We use this model to show that the types of experiment conducted by Dorie et al. could be used to infer spheroid composition and parameters associated with tumour cell lines such as their sensitivity to hypoxia or average rate of proliferation, and note that these observations cannot be conducted within previous continuum models of microbead infiltration into tumour spheroids as they rely on resolving the trajectories of individual microbeads.


Assuntos
Modelos Biológicos , Esferoides Celulares , Células Tumorais Cultivadas , Animais , Fenômenos Biomecânicos , Morte Celular/fisiologia , Hipóxia Celular/fisiologia , Proliferação de Células/fisiologia , Biologia Computacional , Humanos , Esferoides Celulares/citologia , Esferoides Celulares/fisiologia , Células Tumorais Cultivadas/citologia , Células Tumorais Cultivadas/fisiologia
7.
Phys Rev Lett ; 125(6): 068101, 2020 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-32845697

RESUMO

Shape, dynamics, and viscoelastic properties of eukaryotic cells are primarily governed by a thin, reversibly cross-linked actomyosin cortex located directly beneath the plasma membrane. We obtain time-dependent rheological responses of fibroblasts and MDCK II cells from deformation-relaxation curves using an atomic force microscope to access the dependence of cortex fluidity on prestress. We introduce a viscoelastic model that treats the cell as a composite shell and assumes that relaxation of the cortex follows a power law giving access to cortical prestress, area-compressibility modulus, and the power law exponent (fluidity). Cortex fluidity is modulated by interfering with myosin activity. We find that the power law exponent of the cell cortex decreases with increasing intrinsic prestress and area-compressibility modulus, in accordance with previous finding for isolated actin networks subject to external stress. Extrapolation to zero tension returns the theoretically predicted power law exponent for transiently cross-linked polymer networks. In contrast to the widely used Hertzian mechanics, our model provides viscoelastic parameters independent of indenter geometry and compression velocity.


Assuntos
Actinas/química , Fibroblastos/química , Fibroblastos/citologia , Modelos Biológicos , Actinas/fisiologia , Animais , Fenômenos Biomecânicos , Linhagem Celular , Membrana Celular/química , Membrana Celular/fisiologia , Força Compressiva , Cães , Elasticidade , Microscopia de Força Atômica , Miosinas/química , Miosinas/fisiologia , Reologia/métodos , Viscosidade
8.
Int J Comput Dent ; 23(3): 235-244, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32789311

RESUMO

AIM: The traditional hinge axis theory of temporomandibular joint (TMJ) dynamics is increasingly being replaced by the theory of instantaneous centers of rotation (ICR). Typically, ICR determinations are based on theoretical calculations or three-dimensional approximations of finite element models. MATERIALS AND METHODS: With the advent of real-time magnetic resonance imaging (MRI), natural physiologic movements of the TMJ may be visualized with 15 frames per second. The present study employs real-time MRI to analyze the TMJ biomechanics of healthy volunteers during mandibular movements, with a special emphasis on horizontal condylar inclination (HCI) and ICR pathways. The Wilcoxon rank sum test was used to comparatively analyze ICR pathways of mandibular opening and closure. RESULTS: Mean HCI was 34.8 degrees (± 11.3 degrees) and mean mandibular rotation was 26.6 degrees (± 7.2 degrees). Within a mandibular motion of 10 to 30 degrees, the resulting x- and y-translation during opening and closure of the mandible differed significantly (10 to 20 degrees, x: P = 0.02 and y: P < 0.01; 20 to 30 degrees, x: P < 0.001 and y: P = 0.01). Rotation of both 0 to 10 degrees and > 30 degrees showed no significant differences in x- and y-translation. Near occlusion movements differed only for y-translation (P < 0.01). CONCLUSION: Real-time MRI facilitates the direct recording of TMJ structures during physiologic mandibular movements. The present findings support the theory of ICR. Statistics confirmed that opening and closure of the mandible follow different ICR pathways, which might be due to muscular activity discrepancies during different movement directions. ICR pathways were similar within maximum interincisal distance (MID) and near occlusion (NO), which might be explained by limited extensibility of tissue fibers (MID) and tooth contact (NO), respectively.


Assuntos
Côndilo Mandibular , Articulação Temporomandibular , Fenômenos Biomecânicos , Humanos , Imagem por Ressonância Magnética , Mandíbula , Movimento , Amplitude de Movimento Articular , Rotação
9.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 37(4): 608-613, 2020 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-32840077

RESUMO

The decrease of corneal stiffness is the key factor leading to keratoconus, and the corneal collagen fiber stiffness and fiber dispersion are closely related to the corneal biomechanical properties. In this paper, a finite element model of human cornea based on corneal microstructure, namely collagen fiber, was established before and after laser assisted in situ keratomileusis (LASIK). By simulating the Corvis ST process and comparing with the actual clinical results, the hyperelastic constitutive parameters and corneal collagen fiber stiffness modulus of the corneal material were determined before and after refractive surgery. After LASIK, the corneal collagen fiber stiffness modulus increased significantly, and was highly correlated with central corneal thickness (CCT). The predictive relationship between the corneal collagen fiber stiffness modulus and the corresponding CCT before and after surgery was: k 1 before = exp(9.14 - 0.009CCT before), k 1 after = exp(8.82 - 0.008CCT after). According to the results of this study, the central corneal thickness of the patient can be used to estimate the preoperative and postoperative collagen fiber stiffness modulus, and then a personalized corneal model that is more consistent with the actual situation of the patient can be established, providing a theoretical reference for more accurately predicting the safe surgical cutting amount of the cornea.


Assuntos
Córnea , Fenômenos Biomecânicos , Topografia da Córnea , Análise de Elementos Finitos , Humanos , Ceratomileuse Assistida por Excimer Laser In Situ , Miopia
10.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 37(4): 614-621, 2020 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-32840078

RESUMO

As a representative part of the oral system and masticatory robot system, the modeling method of the dental model is an important factor influencing the accuracy of the multi-body dynamic model. Taking the right first molars of the masticatory robot as the research object, an equivalent model, point-contact higher kinematic pair composed of v-shaped surface and sphere surface, was proposed. Firstly, the finite element method was used to analyze the occlusal dynamics of the original model in three static contact cases (intrusive contact, centric occlusion, and extrusive contact) and one dynamic chewing case, and the expected bite force was obtained. Secondly, the Hertz contact model was adopted to establish the analytical expression of the bite force of the equivalent model in three static contact cases. The normal vectors and contact stiffness in the expression were designed according to the expected bite force. Finally, the bite force performance of the equivalent model in three static contact cases and one dynamic chewing case was evaluated. The results showed that the equivalent model could achieve the equivalent bite force of 8 expected items in the static contact cases. Meanwhile, the bite force in the early and late stages of the dynamic chewing case coincides well with the original model. In the middle stage, a certain degree of impact is introduced, but it can be weakened by subsequent trajectory planning. The equivalent modeling scheme of the dental model proposed in this paper further improves the accuracy of the dynamic model of the multi-body system. It provides a new idea for the dynamic modeling of other complex human contacts.


Assuntos
Dente Molar , Fenômenos Biomecânicos , Força de Mordida , Humanos , Mastigação
12.
PLoS One ; 15(7): e0235494, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32701957

RESUMO

The most effective method for harvesting forest fruit is the mechanical vibration harvesting method. During the forced vibration process, the fruit will be shed from the tree when the inertia of the fruit is greater than the fruit's pedicel retention force. In order to study the movement response characteristics of the Ginkgo biloba fruit in depth, for a small Ginkgo biloba fruit tree, the frequency curve of the fruit tree had been obtained in this paper, based on the pulse hammer excitation method, and four resonant frequencies and four trough point frequencies, in the frequency range of 10 Hz~25 Hz, were determined as the test excitation frequency. Through a comparison test between the simulated fruit and the Ginkgo biloba fruit, both the simulated fruit and the real Ginkgo biloba fruit demonstrated good response consistency, and the results had shown that the simulated fruit could be used to replace the Ginkgo biloba fruit. The acceleration response of the resonant frequency and the trough point frequency for two test points of the two primary branches had also been analyzed. It was found that the resonant frequency caused an obvious harmonic response. For the same frequency, the fruit at some points produced a very strong vibrational response, while at other points the fruit was almost stationary. Therefore, it was difficult for a fruit tree to completely shed all its fruit through excitation at a single frequency. It was more difficult to induce a strong vibrational response of fruit on branches of higher stiffness. On the contrary, it was easier to induce a strong vibrational response on more flexible branches regardless of the resonant frequency or the trough point frequency excitation.


Assuntos
Frutas , Ginkgo biloba , Vibração , Fenômenos Biomecânicos , Modelos Teóricos
13.
PLoS One ; 15(7): e0235686, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32658907

RESUMO

Previous research found that below-knee prosthesis users proactively increase their lateral margin-of-stability on their impaired side in anticipation of an impending perturbation when the timing is predictable and potentially directed toward the impaired limb. While knowledge of perturbation timing and direction influences proactive strategies, the consequences of such knowledge and anticipatory behavior on recovery from perturbations is unclear. This study characterized center-of-mass (CoM) dynamics of below-knee prosthesis users and non-impaired controls following a lateral perturbation when the perturbation direction is known but a priori knowledge of the timing of perturbation is either known or unknown. Across groups, CoM displacement during perturbation exposure increased when directed towards the impaired or non-dominant limb with no influence of timing knowledge. In addition, peak CoM displacement was less with known timing irrespective of the perturbation direction. Generally, the CoM displacement during perturbation exposure correlated well with the CoM medial-lateral velocity during unperturbed walking, supporting evidence that human response dynamics to lateral perturbations are influenced by the instantaneous state of the body's momentum.


Assuntos
Membros Artificiais/psicologia , Equilíbrio Postural , Caminhada/fisiologia , Adulto , Fenômenos Biomecânicos , Estudos de Casos e Controles , Feminino , Humanos , Perna (Membro)/fisiologia , Masculino , Adulto Jovem
14.
Nat Commun ; 11(1): 3564, 2020 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-32678102

RESUMO

How does the brain control an effector as complex and versatile as the hand? One possibility is that neural control is simplified by limiting the space of hand movements. Indeed, hand kinematics can be largely described within 8 to 10 dimensions. This oft replicated finding has been construed as evidence that hand postures are confined to this subspace. A prediction from this hypothesis is that dimensions outside of this subspace reflect noise. To address this question, we track the hand of human participants as they perform two tasks-grasping and signing in American Sign Language. We apply multiple dimension reduction techniques and replicate the finding that most postural variance falls within a reduced subspace. However, we show that dimensions outside of this subspace are highly structured and task dependent, suggesting they too are under volitional control. We propose that hand control occupies a higher dimensional space than previously considered.


Assuntos
Mãos/fisiologia , Atividade Motora/fisiologia , Adulto , Fenômenos Biomecânicos , Humanos , Postura/fisiologia , Análise de Componente Principal , Desempenho Psicomotor/fisiologia , Volição/fisiologia , Adulto Jovem
15.
PLoS One ; 15(7): e0235271, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32609761

RESUMO

Calculating forward and inverse kinematics for robotic agents is one of the most time-intensive tasks when controlling the robot movement in any environment. This calculation is then encoded to control the motors and validated in a simulator. The feedback produced by the simulation can be used to correct the code or to implement the code can be implemented directly in the robotic agent. However, the simulation process executes instructions that are not native to the robotic agents, extending development time or making it preferable to validate the code directly on the robot, which in some cases might result in severe damage to it. The use of Domain-Specific Languages help reduce development time in simulation tasks. These languages simplify code generation by describing tasks through an easy-to-understand language and free the user to use a framework or programming API directly for testing purposes. This article presents the language PyDSLRep, which is characterized by the connection and manipulation of movement in mobile robotic agents in the V-Rep simulation environment. This language is tested in three different environments by twenty people, against the framework given by V-Rep, demonstrating that PyDSLRep reduces the average development time by 45.22%, and the lines of code by 76.40% against the Python framework of V-Rep.


Assuntos
Linguagens de Programação , Robótica/métodos , Fenômenos Biomecânicos , Simulação por Computador , Desenho de Equipamento , Humanos , Movimento , Robótica/instrumentação
16.
PLoS One ; 15(7): e0235555, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32645111

RESUMO

The aim of the study was to compare the effects of a 10-week chest-press resistance training on lifting regions in a trained exercise and a none-trained exercise; the barbell bench press (BBP). Thirty-five resistance trained men with 4.2 (± 2.3) years of resistance training experience were recruited. The participants were randomized to attend a resistance program, performing the chest-press, twice per week using either, Smith machine, dumbbells or laying on Swiss ball using a barbell. A six-repetitions maximum (6RM) test was conducted pre- and post-training in the trained chest-press exercise and non-trained BBP to examine lifting velocity, load displacement and the time of the pre-sticking, sticking and post-sticking regions. Additionally, the muscle activity in pectoralis major, triceps brachii, biceps brachii and deltoid anterior was examined. In the post-test, all three chest-press groups decreased lifting velocity and increased the time to reach the sticking- and post-sticking region. Independent of the type of chest-press exercise trained, no differences were observed in vertical displacement or in the muscle activity for the three lifting regions. In general, similar changes in kinematics in trained exercise and those observed in the BBP were observed for all three groups. This indicates that none of the three chest-press exercises (Swiss ball, Smith machine or dumbbells) were specific regarding the lifting regions but displaced a transferability towards the non-trained BBP. However, improved strength altered the sticking region among resistance trained men.


Assuntos
Músculo Esquelético/fisiologia , Treinamento de Resistência/métodos , Fenômenos Biomecânicos , Humanos , Masculino , Tronco/fisiologia , Levantamento de Peso/fisiologia , Adulto Jovem
17.
Int J Nanomedicine ; 15: 4333-4350, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32606681

RESUMO

Background: Different diseases affect both mechanical and chemical features of the involved tissue, enhancing the symptoms. Methods: In this study, using atomic force microscopy, we mechanically characterized human ovarian tissues with four distinct pathological conditions: mucinous, serous, and mature teratoma tumors, and non-tumorous endometriosis. Mechanical elasticity profiles were quantified and the resultant data were categorized using K-means clustering method, as well as fuzzy C-means, to evaluate elastic moduli of cellular and non-cellular parts of diseased tissues and compare them among four disease conditions. Samples were stained by hematoxylin-eosin staining to further study the content of different locations of tissues. Results: Pathological state vastly influenced the mechanical properties of the ovarian tissues. Significant alterations among elastic moduli of both cellular and non-cellular parts were observed. Mature teratoma tumors commonly composed of multiple cell types and heterogeneous ECM structure showed the widest range of elasticity profile and the stiffest average elastic modulus of 14 kPa. Samples of serous tumors were the softest tissues with elastic modulus of only 400 Pa for the cellular part and 5 kPa for the ECM. Tissues of other two diseases were closer in mechanical properties as mucinous tumors were insignificantly stiffer than endometriosis in cellular part, 1300 Pa compared to 1000 Pa, with the ECM average elastic modulus of 8 kPa for both. Conclusion: The higher incidence of carcinoma out of teratoma and serous tumors may be related to the intense alteration of mechanical features of the cellular and the ECM, serving as a potential risk factor which necessitates further investigation.


Assuntos
Microscopia de Força Atômica , Nanopartículas/química , Ovário/patologia , Ovário/ultraestrutura , Adulto , Fenômenos Biomecânicos , Módulo de Elasticidade , Matriz Extracelular/metabolismo , Feminino , Humanos , Pessoa de Meia-Idade
18.
Arthroscopy ; 36(7): 1951-1952, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32624128

RESUMO

Over the past several years, there has been a resurgence of interest in the anterolateral side of the anterior cruciate ligament-injured knee. The 2 most commonly techniques on the anterolateral side for surgically controlling residual rotational instability are anterolateral ligament reconstruction and modified Lemaire lateral extra-articular tenodesis. Several biomechanical studies have shown no or only subtle differences between the 2 procedures. It is time to advance from the biomechanical analyses and direct future work to clinical studies focusing on improving patient selection, surgical morbidity, and longer-term outcomes.


Assuntos
Lesões do Ligamento Cruzado Anterior/cirurgia , Reconstrução do Ligamento Cruzado Anterior , Instabilidade Articular/cirurgia , Tenodese , Fenômenos Biomecânicos , Humanos , Articulação do Joelho/cirurgia
19.
Stud Health Technol Inform ; 272: 249-252, 2020 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-32604648

RESUMO

Manual patient handling is one of the physiological risk factors in care. The scientific focus so far, has primarily been on the analysis of lumbar compression during manual caregiving in order to improve the transfer facilitation of caregivers through technical systems. Reference is made in this context to the supportive functional role of the muscles of the lower limb. To assess biomechanical data for the quantification of lower limb and spine muscle activity in manual patient handling, an experimental study was conducted. A quantitative basis for the analysis of caregiving processes and its risk factors is established by evaluating caregivers' posture, ground reaction force components, and muscle activities during ergonomic and non-ergonomic manual patient handling in a laboratory setting.


Assuntos
Movimentação e Reposicionamento de Pacientes , Fenômenos Biomecânicos , Humanos , Extremidade Inferior , Região Lombossacral , Postura
20.
Zhongguo Yi Liao Qi Xie Za Zhi ; 44(3): 194-198, 2020 Mar 08.
Artigo em Chinês | MEDLINE | ID: mdl-32621424

RESUMO

In order to evaluate the biomechanical stability of titanium alloy screw with different structural parameters under bone remodeling, some three-dimensional finite element models were established and the bone remodeling process after implanting the screw was simulated. Three-dimensional finite element models consist of bone and screw with different lengths and diameters. Bone remodeling process was simulated by user-defined subroutine. It is found that the stress on the bone is concentrated on the groove and root of the internal thread. The screw stress is mainly on the beginning of the thread, and the whole stress decreases along the long axis of the screw. The stress distribution trend of bone and screw did not change significantly during the bone remodeling. The maximum equivalent stress value was different, the maximum equivalent stress on the screw and cancellous bone increased while the maximum equivalent stress value on the cortical bone decreased.


Assuntos
Remodelação Óssea , Parafusos Ósseos , Fenômenos Biomecânicos , Análise de Elementos Finitos , Estresse Mecânico , Titânio
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