Finite element analysis for predicting osteonecrosis of the femoral head collapse based on the preserved angles / 中国修复重建外科杂志

OBJECTIVE@#To establish finite element models of different preserved angles of osteonecrosis of the femoral head (ONFH) for the biomechanical analysis, and to provide mechanical evidence for predicting the risk of ONFH collapse with anterior preserved angle (APA) and lateral preserved angle (LPA).@*METHODS@#A healthy adult was selected as the study object, and the CT data of the left femoral head was acquired and imported into Mimics 21.0 software to reconstruct a complete proximal femur model and construct 3 models of necrotic area with equal volume and different morphology, all models were imported into Solidworks 2022 software to construct 21 finite element models of ONFH with LPA of 45°, 50°, 55°, 60°, 65°, 70°, and 75° when APA was 45°, respectively, and 21 finite element models of ONFH with APA of 45°, 50°, 55°, 60°, 65°, 70°, 75° when LPA was 45°, respectively. According to the physiological load condition of the femoral head, the distal femur was completely fixed, and a force with an angle of 25°, downward direction, and a magnitude of 3.5 times the subject's body mass was applied to the weight-bearing area of the femoral head surface. The maximum Von Mises stress of the surface of the femoral head and the necrotic area and the maximum displacement of the weight-bearing area of the femoral head were calculated and observed by Abaqus 2021 software.@*RESULTS@#The finite element models of ONFH were basically consistent with biomechanics of ONFH. Under the same loading condition, there was stress concentration around the necrotic area in the 42 ONFH models with different preserved angles composed of 3 necrotic areas with equal volume and different morphology. When APA was 60°, the maximum Von Mises stress of the surface of the femoral head and the necrotic area and the maximum displacement of the weight-bearing area of the femoral head of the ONFH models with LPA<60° were significantly higher than those of the models with LPA≥60° ( P<0.05); there was no significant difference in each index among the ONFH models with LPA≥60° ( P>0.05). When LPA was 60°, each index of the ONFH models with APA<60° were significantly higher than those of the models with APA≥60° ( P<0.05); there was no significant difference in each index among the ONFH models with APA≥60° ( P>0.05).@*CONCLUSION@#From the perspective of biomechanics, when a preserved angle of ONFH is less than its critical value, the stress concentration phenomenon in the femoral head is more pronounced, suggesting that the necrotic femoral head may have a higher risk of collapse in this state.

Análisis biomecánico comparativo de recepción a media altura entre jugadores profesionales y amateurs de fútbol / Análise biomecânica comparativa da captura em meia altura entre jogadores profissionais e amadores de futebol / Comparative biomechanical analysis of mid-height reception between professional and amateur soccer players

RESUMEN El fútbol es un deporte de varias acciones motrices, donde la recepción del balón se clasifica como una acción de control a diferentes alturas, velocidades y ángulos. El jugador debe tener la capacidad de receptar el balón para poder generar una acción diferente: un pase, tiro o driblar; su optimización implica mayores probabilidades de rendimiento técnico-táctico. En tal sentido, se planteó como objetivo de la investigación analizar biomecánicamente la técnica de la recepción a media altura en futbolistas profesionales y amateurs a partir de video análisis como método de medición. La investigación fue descriptiva-explicativa de orden correlacional, se analizan cuatro variables del movimiento motriz (D: distancia Recorrida; AM: aceleración máxima; VM: velocidad máxima y AF: amplitud de la articulación femorotibial) a través de video-análisis con Kinovea. Se estudiaron a cinco jugadores profesionales (grupo 1) y 15 de nivel amateur (grupo 2). Los futbolistas de nivel amateur presentaron una mayor media en todas las variables estudiadas, "D" (grupo 1: 72.17cm; grupo 2: 101.27cm; p=0.001), "AM" (grupo 1: 61.84m/s2; grupo 2: 101.73m/s2; p=0.000), "VM" (grupo 1: 8.18m/s; grupo 2: 12.55m/s; p=0.000) y "AF" (grupo 1: 62.6°; grupo 2: 75.2°; p=0.002), lo cual se comporta significativamente diferentes en todos los casos. El análisis biomecánico realizado a futbolistas profesionales y amateurs, en la técnica de recepción del balón a media altura, concluye que en los jugadores amateur requieren un mayor perfeccionamiento técnico, independientemente de su experiencia en competencias.

RESUMO O futebol é um esporte de várias ações motoras, onde a recepção da bola é classificada como uma ação de controle em diferentes alturas, velocidades e ângulos. O jogador deve ter a capacidade de receber a bola para poder gerar uma ação diferente: um passe, um chute ou um drible; sua otimização implica em maiores probabilidades de desempenho técnico-tático. Neste sentido, o objetivo da pesquisa era analisar biomecanicamente a técnica de recepção em meia altura em jogadores profissionais e amadores de futebol utilizando a análise de vídeo como método de medição. A pesquisa foi descritiva-explicativa de ordem correlacional, quatro variáveis de movimento motor (D: distância coberta; MA: aceleração máxima; MV: velocidade máxima e FA: amplitude da articulação femorotibial) foram analisadas através de vídeo-análise com Kinovea. Foram estudados cinco jogadores profissionais (grupo 1) e 15 jogadores amadores (grupo 2). Os jogadores de futebol de nível amador apresentaram uma média maior em todas as variáveis estudadas, "D" (grupo 1: 72,17cm; grupo 2: 101,27cm; p=0,001), "AM" (grupo 1: 61,84m/s2; grupo 2: 101. 73m/s2; p=0,000), "VM" (grupo 1: 8,18m/s2; grupo 2: 12,55m/s; p=0,000) e "AF" (grupo 1: 62,6°; grupo 2: 75,2°; p=0,002), que se comportam de forma significativamente diferente em todos os casos. A análise biomecânica realizada sobre jogadores profissionais e amadores de futebol, na técnica de recepção de bola em altura média, conclui que os jogadores amadores requerem um maior aperfeiçoamento técnico, independentemente de sua experiência em competições.

ABSTRACT Soccer is a sport of various motor actions, where the reception of the ball is classified as a control action at different heights, speeds and angles. The player must have the ability to receive the ball in order to generate a different action: a pass, shot or dribble; its optimization implies greater probabilities of technical-tactical performance. In this sense, the objective of the research was to biomechanically analyze the mid-height reception technique in professional and amateur soccer players using video analysis as a measurement method. The research was descriptive-explanatory of correlational order, four variables of the motor movement (D: distance covered; AM: maximum acceleration; VM: maximum speed and AF: amplitude of the femorotibial joint) are analyzed through video-analysis with Kinovea . Five professional players (group 1) and 15 amateur players (group 2) were studied. The amateur soccer players presented a higher mean in all the variables studied, "D" (group 1: 72.17cm; group 2: 101.27cm; p=0.001), "AM" (group 1: 61.84m/s 2 ; group 2: 101.73m/s 2 ; p=0.000), "VM" (group 1: 8.18m/s; group 2: 12.55m/s; p=0.000) and "AF" (group 1: 62.6°; group 2 : 75.2°; p=0.002), which behaves significantly different in all cases. The biomechanical analysis carried out on professional and amateur soccer players, in the technique of receiving the ball at mid-height, concludes that amateur players require greater technical improvement, regardless of their experience in competitions.

Análisis Biomecánico de una Prótesis de Cadera mediante Elementos Finitos / Biomechanical Analysis of a Hip Prosthesis Using a Finite Element

Resumen En el presente trabajo se plantea un análisis biomecánico de una prótesis de cadera bajo condiciones de cargas estáticas asociadas a actividades cotidianas, en el cual se comparan tres materiales metálicos para la fabricación de una prótesis personalizada a partir de imágenes médicas. Se utilizaron plataformas en la nube de diseño asistido por computadora y de análisis por elementos finitos. Se diseñaron dos modelos de la prótesis a analizar, uno hueco y otro sólido mediante curvas spline paramétricas. Para el análisis biomecánico se requirió un tamaño de malla de 2,537,684 de elementos tetraédricos y 471,335 nodos para estudiar siete casos de posturas para una persona de 75 kg de peso, mismos que se analizaron tomando como materiales base acero inoxidable 316L, aleación Ti-6AL-4V y L-605. Se observó que con actividades tales como trotar, subir y bajar escaleras los materiales 316L y L-605, presentan el riesgo de deformación plástica e inclusive fractura. Los resultados mostraron que el material más idóneo para la fabricación de este tipo de prótesis es el Ti-6Al-4V, además de que este nos permite realizar modelos tanto sólidos como huecos, suponiendo este último, un ahorro de material y proporcionando mayor ligereza en la prótesis.

Abstract This paper shows a biomechanical analysis of a hip prosthesis under conditions of static loads associated with daily activities. For which it compared three metallic materials for the manufacture of a customized prosthesis from medical images, it was used cloud platforms with computer-aided design and finite element analysis. Two models of prosthesis one hollow and the other one solid using parametric spline curves were designed and analyzed. The biomechanical analysis required a mesh size consisting of 2,537,684 tetrahedral elements and 471,335 nodes to study seven cases of postures for a person weighing 75 kg. These cases were analyzed based on 316L stainless steel, Ti-6AL-4V alloy, and another L-605 alloy. It was observed that with activities such as jogging, climbing and descending stairs, materials 316L, and L-605 present the risk of plastic deformation and even fracture. The results show that the most suitable material for the manufacture of this type of prosthesis is the Ti-6Al-4V, which allows us to make both solid and hollow models. Assuming this last material is saved and improves the prosthesis lightness.

Análisis biomecánico de la patada Mawashi Geri Jodan en el kárate-Do / A análise biomecânica do pontapé de Mawashi Geri Jodan no karate-Do / Biomechanical analysis of the Mawashi Geri Jodan kick in karate-Do

Resumen Las expectativas actuales del deporte contemporáneo han impuesto retos que necesariamente implican, desde posiciones de ciencia, la búsqueda constante de nuevas tecnologías que permitan elevar el resultado deportivo de los atletas, de lo cual no ha quedado exento el kárate-do. En la presente investigación, se realizó un estudio de las características biomecánicas que tributan al cumplimiento del patrón técnico de la patada Mawash Geri Jodan, con el objetivo de proponer el procedimiento para su análisis, considerando los indicadores biomecánicos que garantizan su patrón técnico. Para ello, se trabajó con una muestra de seis atletas de los dojos del municipio Pinar del Río, así como una muestra secundaria de seis entrenadores y ocho especialistas. Se emplearon métodos y técnicas científicas de investigación como el analítico-sintético, inductivo-deductivo, análisis de documentos, la observación, la entrevista, la videografía, medición y el criterio de expertos. Para lograr el propósito, se tomó como referencia una metodología, identificando las características biomecánicas que contribuyen al resultado de esta técnica, las que fueron complementadas por el análisis del modelo determinístico construido. Una vez seleccionadas las características biomecánicas que posibilitan la ejecución exitosa de esta técnica, se procedió, mediante el criterio de expertos, al análisis cuantitativo de las variables con su correspondencia, en la incidencia del resultado de la ejecución del movimiento técnico mediante la videograbación. Las características biomecánicas determinadas, que aparecen en el modelo determinístico construido para la técnica, son factibles para el análisis de la calidad de la ejecución de esta patada.

Resumo As expectativas atuais do desporto contemporâneo impuseram desafios que implicam necessariamente, a partir de posições da ciência, a constante procura de novas tecnologias que permitam aos atletas elevar o seu desempenho desportivo, do qual o karate-do não tem sido isento. Na presente investigação foi realizado um estudo das características biomecânicas que contribuem para o cumprimento do padrão técnico do pontapé Mawashi Geri Jodan, com o objectivo de propor o procedimento para a sua análise, considerando os indicadores biomecânicos que garantem o seu padrão técnico. Para isso, foi trabalhada uma amostra de seis atletas dos dojos do município de Pinar del Río, assim como uma amostra secundária de seis treinadores e oito especialistas. Foram utilizados métodos e técnicas de pesquisa científica, tais como análise analítico-sintética, indutivo-dedutiva, análise documental, observação, entrevista, videografia, medição e julgamento por especialistas. Para alcançar o objetivo, tomou-se como referência uma metodologia, identificando as características biomecânicas que contribuem para o resultado desta técnica, as quais foram complementadas pela análise do modelo determinístico construído. Uma vez selecionadas as características biomecânicas que tornam possível a execução bem-sucedida desta técnica, a análise quantitativa das variáveis com sua correspondência na incidência do resultado da execução do movimento técnico por meio da gravação em vídeo foi realizada por meio de critérios de especialistas. As determinadas características biomecânicas que aparecem no modelo determinístico construído para a técnica, são viáveis para a análise da qualidade da execução deste chute.

Abstract The current expectations of contemporary sport have imposed challenges that necessarily imply, from positions of science, the constant search for new technologies that will allow athletes to raise their sporting performance, from which karate-do has not been exempt. In the present research, a study of the biomechanical characteristics that contribute to the fulfillment of the technical pattern of the Mawashi Geri Jodan kick was carried out, with the objective of proposing the procedure for its analysis, considering the biomechanical indicators that guarantee its technical pattern. For this purpose, a sample of six athletes from the dojos of the Pinar del Río municipality was worked on, as well as a secondary sample of six coaches and eight specialists. Scientific research methods and techniques were used, such as analytical-synthetic, inductive-deductive, document analysis, observation, interview, videography, measurement and expert judgment. To achieve the purpose, a methodology was taken as reference, identifying the biomechanical characteristics that contribute to the result of this technique, which were complemented by the analysis of the deterministic model built. Once the biomechanical characteristics that make possible the successful implementation of this technique were selected, the quantitative analysis of the variables with their correspondence in the incidence of the result of the implementation of the technical movement through video recording was carried out by means of expert criteria. The determined biomechanical characteristics that appear in the deterministic model constructed for the technique, are feasible for the analysis of the quality of the execution of this kick.

Establishment of normal foot and common foot disease models using three-dimensional finite element method and biomechanical analysis / 中国组织工程研究

BACKGROUND: In the field of trauma orthopedics, three-dimensional finite element analysis is only a routine means of biomechanical evaluation and internal fixator design and optimization in the treatment of internal fixation of fractures, but also provides new directions for the basic and clinical researches of trauma orthopedics. OBJECTIVE: To establish a three-dimensional finite element model of normal foot, flatfoot, equinus, and foot fracture and to undergo biomechanical analysis. METHODS: One healthy volunteer and patients with flatfoot, equinus, and foot fracture were selected. Their feet were scanned by CT. Three-dimensional finite element modeling and biomechanical analysis were performed by using computer three-dimensional imaging technology according to the CT data. The stress distribution and stress values of each model were then obtained for comparative analysis. The study was approved by the Ethics Committee of Mindong Hospital Affiliated to Fujian Medical University. RESULTS AND CONCLUSION: The three-dimensional finite element models of normal foot, flatfoot, equinus, and foot fracture were established and biomechanical analysis was performed. In the patients with flatfoot, the stress values of the metatarsus and tarsus were significantly increased compared with the normal values. The stress of the equinus was mainly concentrated around the ankle joint, especially on the talus surface. The simple metatarsus fracture had little effect on the stress changes in the tarsus area. The stress in the tarsus area of the Lisfranc injured patients was increased more obviously than in the normal feet. In this study, the three-dimensional finite element modeling and biomechanical analysis of the foot combines computer technology with clinical practice, which provides reference for biomechanical research of human foot. The numericalization of the mechanical data of different foot conditions by mechanical analysis provides important mechanical basis for the clinical treatment of the foot.

Análisis pre mundial del paso de un marchista de élite en pista electrónica / Análise prémundial do passo de um marchista de elite em pista eletrônica / Pre-world analysis of the step of an elite marchist on an electronic track

Problema: en el mundial, los marchistas participan con el más alto nivel de ejecución técnica y con las mejores condiciones físicas, por lo que el análisis de los pasos de un marchista es clave para la obtención de un resultado óptimo. Objetivo: analizar la técnica del paso de un marchista de elite y el comportamiento de las variables de la marcha atlética, pre competencia al mundial de atletismo. Método: al deportista se le aplicó una prueba en una pista electrónica, evaluando las variables cinemáticas: longitud de paso, frecuencia de pasos, tiempo de vuelo y velocidad. Se utilizó ANOVA para determinar diferencias significativas (p ≤0.05). Resultados: en las tres pruebas realizadas, todas las variables incrementaron significativamente, aunque la diferencia más significativa se encontró entre tiempo de vuelo y frecuencia de pasos p=0.0000001, p<0.05. Conclusión: debido a que el tiempo de vuelo se incrementa rápidamente, se debe cuidar que no influya en la ejecución técnica del marchista para que sea más efectiva y así evitar una amonestación o descalificación.

Problem: In the World Athletics Championships, the racewalkers participate with the highest level of technical execution and with the best physical conditions, so the analysis of the steps of a racewalker is key to obtain an optimal result. Objective: To analyze the technique of an elite racewalker and the behavior of the variables of the athletic racewalking, pre-competition to the World Athletics Championships. Method: A test on an electronic track was given to one athlete, evaluating the kinematic variables: step length, step frequency, flight time, and speed. ANOVA was used to determine significant differences (p ≤0.05). Result: In the three tests carried out, all the variables increased significantly, although the most significant difference was found between flight time and step frequency p = 0.0000001, p <0.05. Conclusion: Since the flight time increases rapidly, it must be careful that this not influence the technical execution of the racewalkers, to be more effective, and thus avoid a warning or disqualification.

Problema: No mundial, os marchistas participam com o maior nível de execução técnica e com as melhores condições físicas, é por isso que a análise dos passos de um marchista é a chave para a obtenção de melhores resultados. Objetivo: analisar a técnica de passo de um marchista de elite e o comportamento das variáveis da marcha atlética, pré-competição rumo ao mundial de atletismo. Método: um teste foi aplicado em uma pista eletrônica de um marchista e se estudaram as seguintes variáveis cinemáticas: o comprimento do passo, a frequência de passos, o tempo de voo e a velocidade. ANOVA foi utilizada para determinar as diferenças significativas (p ≤0.05). Resultados: Em todos os três testes realizados, todas as variáveis aumentaram significativamente, embora a diferença mais significativa foi encontrada entre o tempo de voo e a frequência de passos p = 0.0000001, p <0,05. Conclusão: Porque o tempo de voo aumenta rapidamente, deve ser assegurado que não tenha nenhuma influência sobre a execução técnica do marchista, para que seja mais eficaz e, assim, evitar uma advertência ou desqualificação.

Three dimensional finite element biomechanical analysis of unilateral coronal synostosis and reconstruction / 中华整形外科杂志

Objective@#To establish finite element models of skull, fronto-orbital advancement and fronto-orbital distraction osteogenesis of craniosynostosis, to analyze the mechanical characteristics of skull base and fronto-orbital operation area, so as to guide the later application of tractors.@*Methods@#One 6-year-old male patient with unilateral coronal synostosis was enrolled in October 2015. Three-dimensional (3D) computed tomography (CT) scan of skull was performed. DICOM data was imported into Mimics 17.0 for contour extraction and cranial 3D reconstruction. The skull model was processed by Mimics, Geomagic Studio 12.0, Hypermesh 12.0 and other software to establish a three-dimensional finite element model. The unilateral and bilateral fronto-orbital anterior osteotomy models were simulated respectively. The mechanical analysis was performed at point A in forehead area and point B in temporal area. Three different groups of traction forces were loaded: (1) 50 Newton for point A, 50 Newton for point B; (2) 80 Newton for point A and 50 Newton for point B; (3) 100 Newton for point A and 50 Newton for point B, to obtain the optimized traction force.@*Results@#Stress analysis was performed on established cranial finite element model, as well as unilateral and bilateral fronto-orbital advancement procedures. The stress distribution of the anterior and middle cranial fossae was found to be concentrated. After unilateral fronto-orbital advancement, the stress of anterior cranial fossa, especially the affected side, was decreased. The stress on both side in anterior cranial fossa was decreased after bilateral fronto-orbital advancement. After force was applied to point A and point B, the optimum deviation result at supraorbital notch point, midpoint of supraorbital margin, frontal temporal point and frontal zygomatic suture point in 3D (Deviation result of X value: -29.4%, -20.5%, -8.6%, -9.3%; Deviation result of Y value: 20.9%, 31.5%, 73.0%, 539.4%; Deviation result of Z value: 4.4%, 1.9%, 0.1%, 11.8%) demonstrated the application of traction force can inwardly, downwardly and forwardly move the bone flap. The optimized traction was 80 Newton at point A and 50 Newton at point B by preliminary assessment.@*Conclusions@#The finite element analysis of the fronto-orbital advancement can be used for more accurate preoperative simulation, to clarify the influence of fronto-orbital advancement on craniofacial morphology and development, as well as skull base. It also facilitates surgical decision and predicts the postoperative distraction vectors.

Biomechanical analysis of the correlation between sacral tilt displacement and L₅S₁ disc degeneration / 中国骨伤

<p><b>OBJECTIVE</b>To biomechanical analysis of the correlation between sacral tilt displacement and L₅-S₁ disc degeneration.</p><p><b>METHODS</b>From July 2011 to July 2013, 81 patients with lumbar disc herniation and sacroiliac joint disorder including 45 males and 36 females with an average age of (45.39±1.30) years ranging from 18 to 65 years old were selected. The course of the disease ranged from 1 to 144 months with an average of (12.64±2.19) months. All patients were taken lumbar spine lateral X-ray films, the lumbar curvature angle, L₄-L₅ or L₅-S₁ intervertebral gap distance between points, and the lumbosacral angle was measured and correlated analyzed.</p><p><b>RESULTS</b>The lumbar curvature of female patients with L₅S₁DH were significantly larger than male patients [(22.18±8.62)° vs (16.17±4.97)°,<0.05]. Lumbar curvature and lumbosacral angle showed a positive correlation in LDH (=0.48,<0.01,y=7.25+0.38x,<0.01); Male patients with L₄-₅DH were more obvious (=0.55,<0.05, y=5.80+0.43x,<0.01); Female patients with L₅S₁DH were particularly evident(=0.74,<0.01,y=0.91x-5.30,<0.01). The lumbosacral angle and L₄-₅ intervertebral gap was a positive correlation in L₄-₅DH(=0.27,<0.05); While L₅-S₁ intervertebral gap and lumbosacral angle were not correlated(>0.05) in L₅S₁DH.</p><p><b>CONCLUSIONS</b>The sacral tilt displacement and L₅-S₁ disc degeneration were closely related to provide a new understanding philosophy and therapeutic approach for clinical treatment of intractable lumbar L₅S₁DH.</p>

Valoración cuantitativa para la reincorporación ocupacional / Quantitative assessment for the occupational reintegration

Resumen El progreso de la bioingeniería ha permitido el desarrollo de herramientas tecnológicas para cuantificar las variables asociadas al examen físico. En este artículo se presenta la descripción, ventajas y limitaciones de tecnologías para la medición de fuerza, arcos de movimiento, equilibrio y estabilidad, coordinación y marcha. Se proponen también alternativas para uso de estas tecnologías como parte del proceso de valoración de pacientes complejos, ya sea porque se sospeche simulación o porque presenten lesiones graves en las que se requiera sugerir opciones en el proceso de rehabilitación o cierre de caso. En tales circunstancias se identifican alternativas para un diagnóstico más completo que disminuyan la subjetividad del terapeuta y con mayores posibilidades de monitoreo.

Abstract The progress of bioengineering has allowed the development of technological tools to quantify the variables associated to the physical assessment process. The description, advantages and limitations of technologies to measure the strength, range of motion, balance and stability, coordination and gait are shown. Some alternatives are proposed for using those technologies as part of the appreciation process in complex patients, either for any suspicion of simulation or because any serious injury can exist where some alternatives for rehabilitation process are required. In such cases, must be identified some options for a more complete diagnosis, decreasing the subjectivity of the therapist and with more monitoring possibilities.

Simulation and comparison analysis of human mandible projectile injury in different injury conditions / 重庆医学

Objective Finite element numerical simulation technique was applied to simulate the dynamic projectile injury process of human chin in different injury conditions and the mechanism of injury was discussed by using biomechanical analysis . Methods The 3D finite element model of human mandible projective injury was established to simulate the dynamic projectile inju‐ry process of human chin in different injury conditions (high ,medium and low speeds) ,and the simulation results were used to com‐parative analysis of biomechanics .Results The dynamic damage process of human chin projectile injury was simulated successfully in different injury conditions ,and the more serious injury of mandible was caused by faster speed .Conclusion The finite element method can simulate the projectile injury of mandible effectively ,and can provide a new thought and method for basic research and clinical treatment of oral and maxillofacial war injury .

Análise biomecânica de três tipos de conexões protéticas em implantes dentários de diâmetro reduzido / Biomechanical analysis of three types of prosthetic connections on reduced diameter dental implants

Objetivos: avaliar o comportamento biomecânico de três tipos de conexão protética em implantes de diâmetro reduzido. Material e Métodos: implantes com diâmetro 3,25 mm (plataforma 3,4 mm) foram inseridos em polioximetileno (poliacetal) com torque máximo de 45 Ncm e receberam componentes protéticos calcináveis divididos em três grupos: G1: cone-morse (CM), hexágono interno (HI), e Hexágono externo (HE). Todo os pilares foram sobrefundidos em liga de CoCr e aparafusados com torque de 20 Ncm conforme recomendações do fabricante. A avaliação biomecânica ocorreu conforme a norma ISO 14801-2007: carregamento compressivo 30º e fadiga cíclica (f=15Hz, 5 milhões de ciclos) em ambiente seco. A análise estatística foi conduzida usando-se os testes Anova e Tukey (nível de significância 5%). Resultados: os valores compressivos médios foram: G1 (317,43 N), G2 (559,44 N), e G3 (290,83 N). Diferenças signifi cativas foram vistas entre G1 e G2 (p < 0,001) e entre G2 e G3 (p < 0,0001). Não houve diferença entre grupos no teste de fadiga. Os valores correspondentes foram: G1 (190,80 N), G2 (163,25 N), e G3 (141,77 N). Conclusões: todos os grupos demonstraram desempenho biomecânico aceitável

Objectives: to evaluate the biomechanical behavior of three types of prosthetic abutment connections in reduced implant diameters. Material and Methods: 3.25 mm-diameter dental implants (3.4 mm implant platform) were inserted in polyoxymethylene (polyacetal) resin with maximum torque of 45Ncm and received burnout prosthetic abutments divided into three groups: G1: cone-morse (CM), Internal Hex (IH), and External Hex (EH). All abutments were overcast in a CoCr alloy and fastened to 20 Ncm following manufacturer’s instructions. Biomechanical evaluation was performed according to ISO 14801-2007 standards: 30º compressive and fatigue loading (f = 15 Hz, 5 million cycles) in dry environment. Statistical analysis was conducted with Anova and post-hoc Tukey tests (5% signifi cance level). Results: mean compressive values were: G1 (317.43 N), G2 (559.44 N), and G3 (290.83 N). Signifi cant differences were seen between G1 and G2 (p < 0.001) and between G2 and G3 (p < 0.0001). No differences among groups were seen for fatigue loading. The correspondent endurance limits were: G1 (190.80 N), G2 (163.25 N), and G3 (141.77 N). Conclusions: all groups demonstrated acceptable biomechanical performance.

Construction and identification of humerus three-dimensional finite element model in children / 中国组织工程研究

BACKGROUND:Mechanical experiment of finite element numerical simulation is the effective method to research the biomechanical structure of human body. OBJECTIVE:To establish the three-dimensional finite element model of a normal 6-year-old child’s humerus. METHODS:CT images of a 6-year-old child volunteer were imported to the Mimics 10.01 software. The threshold segmentation method was used to rebuild the humerus three-dimensional model. The surface optimization treatment and surface patches dicision were performed on the surface of the model with Geomagic Studio 12.0 software. Then the mesh generation was completed in the software TrueGrid. Final y, the material properties were set and the finite element model was completed. The boundary conditions and constrains were exerted to simulate the three-point-bending test of humeurs. After the simulation, the results were outputted. RESULTS AND CONCLUSION:The humerus finite element model included 3 024 nodes and 18 758 nodes-hexahedron elements. The 0.01 m/s and 3 m/s dynamic loads were loaded respectively, then the central humerus fracture occurred and the load-displacement curve was close to the cadaver test results. The simulation results show that the simulation results of children humerus finite element model are close to the cadaver’s test, and the finite element simulation method can simulate the physical properties of the human skeleton very wel .

Biomechanic Analysis of Lower Extremities in Children and Teenagers with Pes Planus

OBJECTIVE: To analyze the biomechanics of young patients with flat foot or malalignment syndrome of lower extremities and to provide some information and strategies in examining and treating them for other researchers or successive studies. METHOD: Between January 2004 and March 2006, 274 patients were engaged who had been diagnosed as flatfoot in 586 patients aged between 0 and 18. All patients were examined physically by one physiatrist to find other biomechanic abnormalities of lower extremities and to measure resting calcaneal stance position (RCSP) angle, bimalleolar angle (BMA). To detect the existence of scoliosis and the difference in leg length, radiographs were taken of the spine and the lower extremities. Flat foot was defined as when either of the feet had lower than -4degrees degrees of RCSP angle. RESULTS: When comparing the value of RCSP angle between right side and left side, the left side was more pronated than the right side. The value of RCSP angle increased in proportion to age but there are other factors that caused the persistence of foot pronation and ligament laxity. The value of BMA tends to increase in proportion to age. The foot was more pronated, the tibia of the same side was more rotated internally and tibia of the other side was more rotated externally. The most common combined biomechanic abnormality of lower extremities was toe-in gait. CONCLUSION: Because the biomechanic effect of a foot could influence the leg, pelvis of the same side and the other side lower extremity, the flat foot should be regarded as an element of malalignment syndrome, anatomical abnormality, and also functional impairment.

Biomechanical Analysis of the Effect of Pamidronate on Prevention of Osteoporosis in Ovariectomized Rats / 대한정형외과학회잡지

PURPOSE: This study intended to examine the effect of pamidronate, when it was administrated in early estrogen deficiency period, by examining biomechanically bone mass generated in trunkal and extremity bone with bone strength examination. MATERIALS AND METHODS: 17-weeks-old 95 mice of Sprague-Dawley lines were divided into 1st group 28mice, 2nd group 25mice and 3rd group 42mice. The 1st group was sham-operated group, 2nd group underwent bilateral ovariectomy and then injected intravenously normal saline 0.05cc, and 3rd group underwent bilateral ovariectomy and then injected intravenously pamidronate 0.1mg/Kg. RESULTS: The strength of femur, tibia and spine was surveyed with Young' modulus. Femur and spine had a statistically significant difference between 1 and 2 group, 2 and 3 group, and tibia had between 2 and 3 group. CONCLUSION: In early osteoporosis, pamidronate administration is supposed to prevent or decrease osteoporosis and fracture resulting from osteoporosis.

Biomechanical Analysis of Unilateral-Ring Hybrid External Fixation / 대한정형외과연구학회지

The mechanical stiffness of Unilateral-Ring Hybrid External Fixation(URHEF) was analyzed and compared with conventional Ilizarov circular external fixation system and unilateral fixation with DynaExtor(R). Our URHEF is basically a unilateral external fixation system which affords easier incorporation and removal of the Ilizarov rings(200mm in diameter) coupled with connecting clamps at anytime, if needed. It allows controlled axial micromotion in due time. For mechanical test, URHEF system was constructed using a DynaExtor(R) fixed with two or three half pins(6 mm in diameter) attached with two proximal and distal Ilizarov rings fixed with an olive pin and a half pin on each ring. Unilateral fixation system was constructed with a DynaExtor(R) fixed with 2 or 3 half pins. Ring fixation system was constructed with four Ilizarov rings(140mm in diameter). Ilizarov system were assembled into 90degrees-90degrees and 45degrees-13 5degrees configurations with 2 olive pins, respectively. The distance between the center of pylon and the pin-clamp interface was equalized, being 70mm, in all the systems. Stiffness in axial compression, anteroposterior and lateral bending was measured. On axial compression and lateral bending tests, URHEF was stiffer than DynaExtor(R) and Ilizarov systems. On anteroposterior bending test, URHEF was less stiff than 90degrees-50degrees configuration of the Ilizarov system but stiffer than 45degrees-135degrees configuration. Considering the fact that instead of 90degrees-90degrees transfixing pin fixatin system, 45degrees-135degrees configuration system is generally used in clinical practice, URHEF appears to be significantly stiffer than unilateral(DynaExtor(R)) and circular (Ilizarov)fixation systems. This mechanical study implicates that URHEF can be beneficially applied in the clinical use with assurance of mechanical stability.

THE EXPERIMENTAL STUDY OF STRESS FRACTURE OF THE METATARSAL BONES IN NORMAL CHINESE ADULTS / 中国运动医学杂志

The stress fracture is often resulted from forced march, heel-and-toe walking race, trudge over a longdistance etc. The stress fracture in metatarsal bone is very common. After analysis of bearing-force onmetatarsal bone, the feet are simplified as weight-bearing-cantilever beam structure, while the metatarsalbone as lever units which support the bending cantilever. 16 metatarsal bones were taken from freshcadavers of normal Chinese adults. TYPE 2H cantilever stress teeting machine was used for the experiment.This study analyzes the injury mechanism of stress fracture theoretically, the defines limit of stress fractureof the metatarsal bone, and makes biomechanical analysis for the fracture types. This experiment providesthe data and materials for prevention and diagnosis of stress fracture and the possibility of methods andpaths for stress fracture experiment of the biomaterials.