Research progress on biomechanics for internal fixation in tibial plateau fracture / 中国修复重建外科杂志

OBJECTIVE@#To review the biomechanical research progress of internal fixation of tibial plateau fracture in recent years and provide a reference for the selection of internal fixation in clinic.@*METHODS@#The literature related to the biomechanical research of internal fixation of tibial plateau fracture at home and abroad was extensively reviewed, and the biomechanical characteristics of the internal fixation mode and position as well as the biomechanical characteristics of different internal fixators, such as screws, plates, and intramedullary nails were summarized and analyzed.@*RESULTS@#Tibial plateau fracture is one of the common types of knee fractures. The conventional surgical treatment for tibial plateau fracture is open or closed reduction and internal fixation, which requires anatomical reduction and strong fixation. Anatomical reduction can restore the normal shape of the knee joint; strong fixation provides good biomechanical stability, so that the patient can have early functional exercise, restore knee mobility as early as possible, and avoid knee stiffness. Different internal fixators have their own biomechanical strengths and characteristics. The screw fixation has the advantage of being minimally invasive, but the fixation strength is limited, and it is mostly applied to Schatzker typeⅠfracture. For Schatzker Ⅰ-Ⅳ fracture, unilateral plate fixation can be used; for Schatzker Ⅴand Ⅵ fracture, bilateral plates fixation can be used to provide stronger fixation strength and avoid the stress concentration. The intramedullary nails fixation has the advantages of less trauma and less influence on the blood flow of the fracture end, but the fixation strength of the medial and lateral plateau is limited; so it is more suitable for tibial plateau fracture that involves only the metaphysis. Choosing the most appropriate internal fixation according to the patient's condition is still a major difficulty in the surgical treatment of tibial plateau fractures.@*CONCLUSION@#Each internal fixator has good fixation effect on tibial plateau fracture within the applicable range, and it is an important research direction to improve and innovate the existing internal fixator from various aspects, such as manufacturing process, material, and morphology.

Research progress of finite element method in the biomechanics of the orbit / 国际眼科杂志(Guoji Yanke Zazhi)

The finite element method(FEM)is a widely employed mathematical technique in mechanical research that divides an object into discrete and interacting finite elements. Medically, finite element analysis(FEA)enables the simulation of biomechanical experiments that are challenging to conduct. Orbital surgery poses significant challenges to ophthalmologists due to its inherent difficulty and steep learning curve. FEM enables the simulation and analysis of the mechanical properties of orbital tissue, offering a novel approach for diagnosing and treating orbital-related diseases. With technological advancements, FEM has significantly matured in the diagnosis and treatment of orbital diseases, becoming a popular area of research in orbital biomechanics. This paper reviewed the latest advancements in orbital FEM, encompassing the development of orbital FEA models, simulation of orbital structure, and its application in orbital-related diseases. Additionally, the limitations of FEM and future research directions are also discussed. As a digital tool for auxiliary diagnosis and treatment, orbital FEA will progressively unlock its potential for diagnosing and treating orbital diseases alongside technological advancements.

Effect of small incision lenticule extraction on the treatment of myopia patients and the impact on corneal biomechanics / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To investigate the effect of small incision lenticule extraction(SMILE)on the treatment of myopia patients, and the impact on corneal biomechanics.METHODS:Retrospective study. A total of 120 myopic patients(240 eyes)who were scheduled to undergo corneal refractive surgery in Anyang Eye Hospital from January 2020 to December 2021 were selected. The patients were divided into SMILE group(64 patients, 128 eyes)and transepithelial photorefractive keratectomy(TransPRK)group(56 patients, 112 eyes)according to the surgical treatment method. The two groups were compared in terms of uncorrected visual acuity, corneal biomechanics, corneal endothelial cell count, posterior corneal surface height and corneal surface regularity index at 1, 7 d, 1, 3, 6 mo and 1 a after surgery, and surgical complications.RESULTS:The uncorrected visual acuity of the SMILE group at 1, 7 d and 1 mo after surgery was better than that of the TransPRK group(all P<0.001), but there was no statistically significant difference between the groups at 3, 6 mo and 1 a after surgery(all P>0.05). Compared with preoperative values, corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure, corneal resistance factor, and corneal hysteresis in both groups showed a first decreasing and then increasing trend after surgery. The corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure, corneal resistance factor, and corneal hysteresis in the SMILE group at 1, 7 d and 1 mo after surgery were higher than those in the TransPRK group(all P<0.05), but there was no statistically significant difference between the groups at 3, 6 mo and 1 a after surgery(all P>0.05). There were no significant changes of corneal endothelial cell count and corneal posterior surface height in the two groups after surgery(all P>0.05). Furthermore, corneal surface regularity index of the two groups showed a first increasing and then decreasing trend after surgery, with no statistically significant difference between the groups(P>0.05), and there was no statistically significant difference in the incidence of postoperative complications between the groups(P>0.05).CONCLUSION:Compared with TransPRK, SMILE has less influence on corneal biomechanics, and better visual recovery in the early stage. There is no difference in long-term visual acuity between the two surgeries, and both have good safety and effectiveness.

Stress distribution in peri-implant bone, implants, and prostheses: 3D-FEA of marginal bone loss and prosthetic design / Distribuição de estresse no osso peri-implantar, implantes e próteses: análise 3D-FEA de perda óssea marginal e design protético

Objective: In response to the demand for dental implants, extensive research has been conducted on methods for transferring load to the surrounding bone. This study aimed to evaluate the stresses on the peripheral bone, implants, and prostheses under scenarios involving of the following variables: prosthesis designs, vertical bone heights, load angles, and restorative materials. Material and Methods: Three implants were inserted in the premolar and molar regions (5-6-7) of the two mandibular models. Model 1 represented 0 mm marginal bone loss and Model 2 simulated 3 mm bone loss. CAD/CAM-supported materials, hybrid ceramic (HC), resin-nano ceramic (RNC), lithium disilicate (LiSi), zirconia (Zr), and two prosthesis designs (splinted and non-splinted) were used for the implant-supported crowns. Forces were applied vertically (90°) to the central fossa and buccal cusps and obliquely (30°) to the buccal cusps only. The stresses were evaluated using a three-dimensional Finite Element Analysis. Results: Oblique loading resulted in the highest stress values. Of the four materials, RNC showed the low stress in the restoration, particularly in the marginal area. The use of different restorative materials did not affect stress distribution in the surrounding bone. The splinted prostheses generated lower stress magnitude on the bone, and while more stress on the implants were observed. Conclusion: In terms of the stress distribution on the peri-implant bone and implants, the use of different restorative materials is not important. Oblique loading resulted in higher stress values, and the splinted prosthesis design resulted in lower stress (AU)

Objetivo: Em resposta à demanda por implantes dentários, extensa pesquisa foi realizada sobre métodos para transferir carga ao osso circundante. Este estudo buscou avaliar os estresses no osso periférico, implantes e próteses em cenários que envolvem as seguintes variáveis: designs de próteses, alturas ósseas verticais, ângulos de carga e materiais restauradores. Material e Métodos: Três implantes foram inseridos nas regiões dos pré-molares e molares (5-6-7) de dois modelos de mandíbula. O Modelo 1 representou perda óssea marginal de 0 mm e o Modelo 2 simulou perda óssea de 3 mm. Materiais suportados por CAD/CAM, cerâmica híbrida (HC), cerâmica nano-resina (RNC), dissilicato de lítio (LiSi), zircônia (Zr) e dois designs de próteses (sintetizadas e não-sintetizadas) foram utilizados para as coroas suportadas por implantes. Forças foram aplicadas verticalmente (90°) à fossa central e cúspides bucais e obliquamente (30°) apenas às cúspides bucais. Os estresses foram avaliados usando Análise de Elementos Finitos tridimensional. Resultados: Cargas oblíquas resultaram nos valores mais altos de estresse. Entre os quatro materiais, RNC mostrou baixo estresse na restauração, especialmente na área marginal. O uso de diferentes materiais restauradores não afetou a distribuição de estresse no osso circundante. Próteses sintetizadas geraram menor magnitude de estresse no osso, enquanto mais estresse nos implantes foi observado. Conclusão: Em termos de distribuição de estresse no osso peri-implantar e implantes, o uso de diferentes materiais restauradores não é crucial. Cargas oblíquas resultaram em valores mais altos de estresse, e o design de prótese sintetizada resultou em menor estresse. (AU)

Variables biomecánicas del penalti en futbolistas de las categorías sub-12 y sub-17

Introducción: El estudio de los patrones del movimiento técnico deportivo implica analizar sus componentes biomecánicos, teniendo en cuenta el carácter multifactorial del rendimiento deportivo. Objetivo: Describir la mecánica del movimiento del tiro penalti en futbolistas categorías sub-12 y sub-17. Métodos: Estudio cuasi experimental de orden correlativo. Se estudiaron ocho variables biomecánicas: centro de gravedad en sus dos ejes, inclinación corporal, ángulos femorotibial antes del contacto, ángulos femorotibial luego del contacto, velocidad, aceleración y acierto. Se seleccionaron dos grupos independientes de 30 futbolistas del género masculino, se clasificaron por categorías sub-12 y sub-17, y se analizó su rendimiento mediante videoanálisis. Resultados: Hubo diferencias significativas a favor de la categoría sub-17 en las variables centro de gravedad en el eje X (p = 0,000), en inclinación corporal (p = 0,000), en velocidad (p = 0,000), y en aceleración y acierto (p = 0,000); y diferencias no significativas en el resto (centro de gravedad eje Y: p = 0,267; ángulos femorotibial antes del contacto: p = 0,459; ángulos femorotibial luego del contacto: p = 0,446; y aciertos: p = 0,226). Conclusiones: Todos los rangos promedios sobresalieron en la categoría sub-17, excepto en la variable aciertos, lo que implicó una mayor velocidad y aceleración del pie durante la ejecución del tiro a penal. Sin embargo, la precisión, como componente coordinativo, resultó fundamental en la efectividad del disparo.

Introduction: The study of the patterns of technical sports movement involves analyzing its biomechanical components, taking into account the multifactorial nature of sports performance. Objective: To describe the mechanics of the movement of the penalty kick in U-12 and U-17 football players. Methods: Quasi-experimental study of a correlative order. Eight biomechanical variables were studied: center of gravity in its two axes, body inclination, femorotibial angles before contact, femorotibial angles after contact, speed, acceleration and success. Two independent groups of 30 male footballers were selected, classified by U-12 and U-17 categories, and their performance was analysed through video analysis. Results: There were significant differences in favor of the sub-17 category in the variables center of gravity on the X axis (p = 0.000), body inclination (p = 0.000), speed (p = 0.000), and acceleration and accuracy (p = 0.000); and non-significant differences in the rest (center of gravity Y-axis: p = 0.267; femorotibial angles before contact: p = 0.459; femorotibial angles after contact: p = 0.446; and correct answers: p = 0.226). Conclusions: All the average ranges stood out in the U-17 category, except in the variable hits, which implied a greater speed and acceleration of the foot during the execution of the penalty kick. However, accuracy, as a coordinating component, was fundamental in the effectiveness of the shot.

Assessing the effect of prophylactic ankle taping on ankle and knee biomechanics during landing tasks in healthy individuals: A cross-sectional observational study

ABSTRACT BACKGROUND: Current research supports the fact that prophylactic ankle taping (AT) is effective in preventing ankle injuries in amateur and elite sports athletes. OBJECTIVE: This study aimed to investigate the effect of AT on balance, knee valgus during drop jump and single-leg countermovement jump (SL-CMJ) landings, and ankle range of motion (ROM) restriction in healthy participants. DESIGN AND SETTING: A cross-sectional observational study was conducted at the Universidad Europea de Madrid, Madrid, Spain. METHODS: Participants: Thirty-nine healthy individuals participated in this study and performed the movements under two conditions (with and without tape). Outcome measurements: ankle ROM, balance, SL-CMJ height, flight time, ground time, and knee valgus. Before any intervention, a random process was developed with a 1:1 allocation ratio, and the participants were assigned to groups A (tape-no tape) and B (no tape-tape). RESULTS: Significant differences between tape and no-tape moments were observed for drop jump knee valgus flexion (P = 0.007), with an increase in knee valgus in participants with ankle taping. Similarly, the Y-balance testshowed a significant decrease in all variables (P = 0.001 and), ankle dorsiflexion (P = 0.001) in participants with ankle taping. CONCLUSIONS: AT is effective for immediate ankle ROM restriction. However, an increase in knee valgus during drop jump task and a decrease in lower limb balance were observed during drop jump task. Based on these results, it can be concluded that AT application in healthy individuals should not be recommended as it results in increase in injury risk factors.

Is ankle taping effective to limit the ankle dorsiflexion in a single-training session? An observational study in semi-professional basketball players

ABSTRACT BACKGROUND: Ankle taping (AT) is effective in preventing ankle sprain injuries in most common sports and is employed in rehabilitation and prevention sports. OBJECTIVE: This study aimed to investigate the effectiveness of AT to restricting excessive frontal plane ankle movements in semi-professional basketball players throughout the training session. DESIGN AND SETTING: A cross-sectional study was performed at the Universidad Europea de Madrid. METHODS: Forty male and female semi-professional basketball players were divided into two groups. The ankle dorsiflexion range of motion (ROM) and interlimb asymmetries in a weight-bearing lunge position were evaluated at four time points: 1) with no tape, 2) before practice, at 30 min of practice, and 3) immediately after practice. RESULTS: In male basketball players, no differences were observed in the right and left ankles between the baseline and 30 min and between baseline and 90 min of assessment. In female athletes, significant differences were reported between baseline and pre-training assessments for the right ankle and also significant differences between baseline and 90 min in both ankles. CONCLUSIONS: Ankle taping effectively decreased the ankle dorsiflexion ROM in male and female basketball players immediately after application. However, ROM restriction was very low after 30 and 90 min, as assessed in a single basketball practice. Therefore, the classic taping method should be revised to develop new prophylactic approaches, such as the implementation of semi-rigid bracing techniques or the addition of active stripes during training or game pauses.

A novel validation approach shows new, solid reasons why vertical jump height should not be used to predict leg power / Uma nova abordagem de validação acrescenta fortes razões para não usar a altura do salto vertical como um indicador de potência das pernas / Un novedoso enfoque de validación añade sólidas razones para no utilizar la altura del salto vertical como predictor de la potencia de piernas

Abstract Jump height continues to be widely used to predict power in humans. Individual progress is often monitored on the basis of estimated power, but prediction equations are based on group data. The objective of the study was to show that vertical jump performance (vJP) and mechanical power are poorly associated, particularly within individuals. Two experiments are presented. First, 52 physically active male college students performed five maximal vertical jumps each. Second, three young male participants performed 50 maximal jumps each. Participants rested for 1 minute between jumps. vJP was calculated from kinematic data as peak body center of mass (BCOM) minus standing BCOM; peak power (PEAKPWR) was calculated from the vertical ground reaction force registered by a force plate, and average power (MEANPWR) during propulsion from the change in potential energy of BCOM. Regression analyses were performed using standardized vJP scores as the predictor variable and standardized power scores as the resulting variables, expecting an identity function of y = x (intercept = 0, slope = 1) and R2 = 1. In experiment 1, the model for zPEAKPWR R2 = 0.9707 (p < 0.0001) but slope (0.3452) ≠ 1 (p < 0.0001). The model for zMEANPWR R2 = 0.9239 (p < 0.0001); nevertheless, slope (0.4257) ≠ 1 (p < 0.0001). In experiment 2, all individual models for zPEAKPWR and zMEANPWR resulted in poor associations (R2 ≤ 0.21) and slopes ≠ 1 (p≤0.001). In conclusion, regression analysis for individuals, and even for groups, confirms that vJP is a poor predictor of mechanical power.

Resumo A altura do salto ainda é amplamente usada para prever a potência em humanos. O progresso individual é frequentemente monitorado usando a estimativa de potência, mas as equações de previsão são baseadas em dados de grupo. O objetivo do estudo é demonstrar que a altura do salto vertical (ASv) e a potência mecânica têm uma correlação débil, principalmente em um mesmo indivíduo. São apresentados dois experimentos: primeiro, 52 estudantes universitários fisicamente ativos realizaram cinco saltos verticais máximos cada um; segundo, três participantes do sexo masculino realizaram 50 saltos máximos cada um. Os participantes descansaram por 1 minuto entre os saltos. A ASv foi calculada a partir de dados cinemáticos como a posição mais alta do centro de massa corporal (CMC) menos o CMC em pé; a potência de pico (PEAKPWR) foi calculada a partir da força de reação vertical registrada por uma plataforma de força e a potência média (MEANPWR) durante a propulsão a partir da mudança na energia potencial do CMC. As análises de regressão foram realizadas usando os escores da ASv padronizados como variável preditora e os escores de potência padronizados como variáveis de resultado, com a expectativa de obter uma função de identidade y = x (interceptação = 0, inclinação = 1) e R2 = 1. No experimento 1, o modelo para zPEAKPWR produziu R2 = 0,9707(p < 0,0001), mas a inclinação (0,3452) ≠ 1 (p = 8,7x10-15). O modelo para zMEANPWR apresentou R2 = 0,9239 (p < 0,0001); no entanto, a inclinação (0,4257) ≠ 1 (p = 1,15x10-5). No experimento 2, todos os modelos individuais para zPEAKPWR e zMEANPWR apresentaram associações débeis (R2 ≤ 0,21) e inclinações ≠ 1(p ≤ 0,001). Em conclusão, a análise de regressão para indivíduos e até mesmo para grupos confirma que a ASv é um indicador débil da potência mecânica.

Resumen La altura del salto se sigue usando ampliamente para predecir la potencia en seres humanos. El progreso individual, a menudo, se monitorea usando una estimación de la potencia, pero las ecuaciones de predicción se basan en datos grupales. El estudio pretende demostrar que la altura del salto vertical (ASv) y la potencia mecánica tienen una pobre correlación, particularmente en un mismo individuo. Se presentan dos experimentos; primero, 52 estudiantes universitarios físicamente activos ejecutaron cinco saltos verticales máximos cada uno; segundo, tres participantes masculinos ejecutaron 50 saltos máximos cada uno. Los participantes descansaron 1 minuto entre saltos. ASv se calculó a partir de los datos cinemáticos como posición más alta del centro de masa corporal (CDM) menos CDM de pie; la potencia pico (PEAKPWR) se calculó a partir de la fuerza vertical de reacción registrada por una plataforma de fuerza y la potencia promedio (MEANPWR) durante la propulsión a partir del cambio en la energía potencial del CDM. Se realizaron análisis de regresión usando puntajes estandarizados de ASv como la variable predictora y puntajes estandarizados de potencia como las variables resultantes, con la expectativa de obtener una función de identidad y = x (intercepto = 0, pendiente = 1) y R2 = 1. En el experimento 1, el modelo para zPEAKPWR arrojó R2 = 0.9707 (p <.0001) pero la pendiente (0.3452) ≠ 1 (p = 8.7x10-15). El modelo para zMEANPWR dio R2 = 0.9239 (p < .0001); sin embargo, la pendiente (0.4257) ≠ 1 (p = 1.15x10-5). En el experimento 2, todos los modelos individuales para zPEAKPWR y zMEANPWR arrojaron asociaciones débiles (R2 ≤ 0.21) y pendientes ≠ 1 (p ≤ .001). En conclusión, el análisis de regresión para individuos y aún para grupos confirma que la ASv es un pobre predictor de la potencia mecánica.

La biomecánica aplicada a la técnica de pitcheo en lanzadores de béisbol

El deporte como fenómeno social, se desarrolla en la actualidad simultáneamente con los adelantos de la ciencia y la tecnología; en este contexto, juega un papel importante la biomecánica que asegura las bases para un verdadero entrenamiento técnico, de ahí que el trabajo está dirigido al uso de la biomecánica en la técnica de pitcheo. Para dar respuesta a esta temática se concibe como objetivo aplicar estudios biomecánicos a la técnica de pitcheo en los lanzadores del equipo de béisbol La Isla de la Juventud. Se utilizaron como métodos el análisis de documentos, la revisión bibliográfica, la observación científica, la entrevista y la técnica del análisis de video con ayuda de un Dron; ello permitió medir magnitudes y valorar el comportamiento de las características que poseen los movimientos ejecutados por los lanzadores objeto de estudio. También, se emplearon dos técnicas de mediciones, una a través de la filmación y otra por procesamiento cinemático con el uso de los softwares como Tracker y Kinovea. La muestra estuvo conformada por ocho sujetos, distribuidos en tres atletas, dos entrenadores y tres investigadores; esto permitió determinar las características de la distancia de paso, ángulo que forma el brazo de lanzar con respecto a la cabeza, altura de la pelota y la velocidad de la pelota ejecutados por los lanzadores investigados.

O esporte, como fenômeno social, está se desenvolvendo simultaneamente com os avanços da ciência e da tecnologia; nesse contexto, a biomecânica desempenha um papel importante para garantir a base de um verdadeiro treinamento técnico, portanto, o trabalho visa ao uso da biomecânica na técnica de arremesso. Para responder a essa questão, o objetivo foi aplicar estudos biomecânicos à técnica de arremesso nos arremessadores do time de beisebol La Isla de la Juventud. Os métodos utilizados foram a análise de documentos, a revisão bibliográfica, a observação científica, a entrevista e a técnica de análise de vídeo com a ajuda de um drone, o que permitiu medir as magnitudes e avaliar o comportamento das características dos movimentos executados pelos arremessadores em estudo. Além disso, foram utilizadas duas técnicas de medição, uma por meio de filmagem e outra por meio de processamento cinemático com o uso de softwares como o Tracker e o Kinovea. A amostra foi composta por oito sujeitos, distribuídos em três atletas, dois técnicos e três pesquisadores, o que nos permitiu determinar as características da distância de arremesso, do ângulo do braço de arremesso em relação à cabeça, da altura da bola e da velocidade da bola executada pelos arremessadores investigados.

Sport as a social phenomenon, currently develops simultaneously with the advances of science and technology; in this context, biomechanics plays an important role that ensures the bases for true technical training; hence the work is directed to the use of biomechanics in throwing technique. To respond to this issue, the objective is to apply biomechanical studies to the throwing technique in the throwers of the La Isla de la Juventud baseball team. Document analysis, bibliographic review, scientific observation, interview and the technique of video analysis with the help of a drone were used as methods; this made it possible to measure magnitudes and assess the behavior of the characteristics of the movements executed by the throwers under study. Also, two measurement techniques were used, one through filming and the other by kinematic processing with the use of software such as Tracker and Kinovea. The sample consisted of eight subjects, divided into three athletes, two coaches and three researchers; this allowed to determine the characteristics of the throw distance, the angle formed by the throwing arm with respect to the head, the height of the ball, and the speed of the ball executed by the investigated throwers.

Fatigue-life and stress distribution of a glass-ceramic under different loading conditions

Abstract This study aimed to evaluate the effect of different loading conditions on the mechanical behavior and stress distribution of a leucite-reinforced glass-ceramic. Plate-shaped ceramic specimens were obtained from leucite-reinforced glass-ceramic (1.5 × 8.4 × 8.3 mm) and adhesively cemented to a dentin analog substrate. Monotonic and cyclic contact fatigue tests were performed to simulate sphere-to-flat contact, using a 6 mm diameter spherical piston; and flat-to-flat contact, using a 3 mm diameter flat piston. For the monotonic test (n=20), a gradual compressive load (0.5 mm/min) was applied to the specimen using a universal testing machine. Failure load data were analyzed with Weibull statistics. The cyclic contact fatigue test was performed using protocols (load and a number of cycles) defined by the boundary technique (n=30). Fatigue data were analyzed using an inverse power law relationship and Weibull-lifetime distribution. The stress distribution was investigated using Finite Element Analysis (FEA). The monotonic and the fatigue Weibull modulus were similar among the two contact conditions. In fatigue, the slow crack growth exponent was greater for sphere-to-flat contact, which indicates that the load level had a greater effect on the specimen's probability of failure. In conclusion, FEA showed different stress distribution for the tested loading conditions. The stress distribution and probability of fatigue failure of specimens tested in sphere-to-flat contact showed greater dependency to load level.

Resumo O objetivo deste estudo é avaliar o efeito de diferentes condições de carregamento no comportamento mecânico e na distribuição de tensões de uma vitrocerâmica reforçada com leucita. Amostras cerâmicas em forma de lâminas foram obtidas a partir de vitrocerâmica reforçada com leucita (1,5 × 8,4 × 8,3 mm) e cimentadas adesivamente a um substrato análogo de dentina. Ensaios de carga de compressão monotônica e fadiga foram realizados para simular o contato esfera-plano, usando um pistão esférico de 6 mm de diâmetro; e contato plano com plano, usando um pistão plano de 3 mm de diâmetro. Para o ensaio de carga de compressão monotônica (n=20), foi aplicada uma carga compressiva gradual (0,5 mm/min) ao corpo-de-prova usando uma máquina de ensaio universal. Os dados de carga de fratura foram analisados de acordo com a distribuição de Weibull. O teste de fadiga foi realizado com os protocolos (carga e número de ciclos) definidos pela técnica de boundary (n=30). Os dados de fadiga foram analisados usando uma relação de tempo de vida - tensão de lei da potência inversa (IPL- inverse power law). A distribuição de tensões foi investigada usando análise de elementos finitos (AEF). O módulo de Weibull para teste de compressão monotônico e de fadiga foram semelhantes entre as duas condições de contato. Em fadiga, o expoente de crescimento sub-crítico da trinca foi maior para o contato esfera-plano, o que indica que o nível de carga teve um efeito maior na probabilidade de falha do corpo-de-prova. Em conclusão, AEF apresentou distribuição de tensões diferente para as condições de carregamento testadas. A distribuição de tensões e a probabilidade de falha em fadiga dos corpos-de-prova testados utilizando o contato esfera-plano apresentaram maior dependência do nível de carga.

Research Progress and Forensic Application of Human Vascular Finite Element Modeling and Biomechanics / 法医学杂志

The finite element method (FEM) is a mathematical method for obtaining approximate solutions to a wide variety of engineering problems. With the development of computer technology, it is gradually applied to the study of biomechanics of human body. The application of the combination of FEM and biomechanics in exploring the relationship between vascular injury and disease, and pathological mechanisms will be a technological innovation for traditional forensic medicine. This paper reviews the construction and development of human vascular FEM modeling, and its research progress on the vascular biomechanics. This paper also looks to the application prospects of FEM modeling in forensic pathology.

Design and validation of a novel knee biomechanical test method / 生物医学工程学杂志

A novel structural dynamics test method and device were designed to test the biomechanical effects of dynamic axial loading on knee cartilage and meniscus. Firstly, the maximum acceleration signal-to-noise ratio of the experimental device was calculated by applying axial dynamic load to the experimental device under unloaded condition with different force hammers. Then the experimental samples were divided into non-specimen group (no specimen loaded), sham specimen group (loaded with polypropylene samples) and bovine knee joint specimen group (loaded with bovine knee joint samples) for testing. The test results show that the experimental device and method can provide stable axial dynamic load, and the experimental results have good repeatability. The final results confirm that the dynamic characteristics of experimental samples can be distinguished effectively by this device. The experimental method proposed in this study provides a new way to further study the biomechanical mechanism of knee joint structural response under axial dynamic load.

Role of lymphatic system in coronary heart disease based on theory of combined phlegm and stasis / 中国中药杂志

According to the traditional Chinese medicine(TCM) theory, coronary heart disease(CHD) is mainly caused by heart vessel obstruction due to Qi stagnation, blood stasis, and phlegm turbidity. Chest impediment with combined phlegm and stasis is a common syndrome of CHD, with the manifestations of chest tightness, chest pain, and asthma. Lymphatic system is one of the important immune systems in the human body and has a close relationship with the Qi and blood movement in TCM. The dysfunction of the lymphatic system may lead to metabolism disorders, the generation of dampness pathogen which turns into sticky and difficult-to-dissolve phlegm turbidity. Moreover, it can affect blood circulation and coagulation, causing slow blood flow, increased blood viscosity, and microcirculation disorders. Alterations in lymphatic hydrodynamics may affect the interaction between blood circulation and the lymphatic system. A variety of small molecule drugs and TCM can treat cardiovascular diseases by targeting the lymphatic system. This review discusses the role of the lymphatic system in CHD based on the theory of combined phlegm and stasis, involving the influences of mechanical factors on lymphatic function and the effects and pharmacological mechanisms of TCM and chemicals that target lymphocyte function and lymphatic circulation. By expounding the development process of combined phlegm and stasis in CHD from the lymphatic system, this paper aims to provide new ideas for deciphering pharmacological mechanisms of TCM for resolving phlegm and stasis.

Mechanical effects of needle texture on acupoint tissue / 中西医结合学报

OBJECTIVE@#This study aims to clarify how the stimulation of acupuncture points is achieved by needles with different surface texture during acupuncture; it also seeks to lessen injury at the insertion site and increase the therapeutic efficacy of acupuncture, by simulating the mechanical effects of various needle surface patterns on Zusanli (ST36) without changing the radius of acupuncture needles.@*METHODS@#Five acupuncture needle models with different surface patterns, including the smooth needle, the lined needle, the ringed needle, the left-hand threaded needle and the right-hand threaded needle, and a layered model of the Zusanli acupoint were used to investigate how to reduce tissue damage and increase stimulation during acupuncture treatment. Puncturing of the skin as well as lifting-inserting and twisting needle manipulations were simulated using these models, and the degree of damage and force of stimulation caused by the acupuncture needles with different surface patterns during acupuncture were compared.@*RESULTS@#The smooth needle and the lined needle caused the least tissue damage during insertion, while the left-hand threaded and the right-hand threaded needles caused the most damage. The ringed needle, the left-hand threaded needle and the right-hand threaded needle stimulated the acupoint tissue more during lifting-inserting manipulations, while the lined needle and the smooth needle produced less stimulation. The stimulation of the lined needle on the acupoint tissue was the largest during twisting manipulation, whereas the left-hand threaded needle and the right-hand threaded needle had smaller effects. In lifting-inserting and twisting manipulations, both the left-hand threaded needle and right-hand threaded needle provided more stimulation, but the torsion direction in which they produced better stimulation was the opposite.@*CONCLUSION@#According to the simulation results, the ringed pattern enhances stimulation best in the lifting-inserting manipulation, whereas the lined pattern enhances stimulation best in the twisting manipulation. Both the right-hand and left-hand thread patterns have certain enhancing effects in these two operations. Taking the geometric properties of the pattern into account, the left-hand thread pattern and the right-hand thread pattern have the geometric characteristics of both the lined pattern and the ringed pattern. To conclude, a pattern perpendicular to the movement direction during the acupuncture manipulation creates more stimulation. These results have significance for future needle design. Please cite this article as: Sun MZ, Wang X, Li YC, Yao W, Gu W. Mechanical effects of needle texture on acupoint tissue. J Integr Med. 2023; 21(3): 254-267.

Efficacy of epithelial-off accelerated corneal cross-linking in the treatment of advanced keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the efficacy of epithelial-off accelerated corneal cross-linking(CXL)in the treatment of advanced keratoconus.METHODS: A retrospective study was performed on data collected from 32 patients(43 eyes)with advanced keratoconus who underwent epithelial-off accelerated CXL at Ningxia Eye Hospital from April 2020 to December 2021. Slit-lamp, intraocular pressure, uncorrected visual acuity(UCVA), corrected visual acuity, specular microscope, Pentacam and Corvis ST were tested before and at 1, 3 and 6mo after surgery. Preoperative and postoperative corneal condition, UCVA, best corrected visual acuity(BCVA)and the values of corneal endothelial, maximum keratometry(Kmax), thinnest corneal thickness(TCT), anterior and posterior surfaces of the cornea K1, K2, biomechanically corrected intraocular pressure(bIOP), applanation time 1(A1T), applanation length 1(A1L), applanation velocity 1(A1V), applanation time 2(A2T), applanation length 2(A2L), applanation velocity 2(A2V), highest concavity deformation amplitude(HCDA), radius at highest curvature(HCR), highest concavity peak distance(HCPD)and stiffness parameter at first applanation(SP-A1)were recorded.RESULTS: There were differences between UCVA(LogMAR; 1.06±0.49, 0.78±0.39)and BCVA(LogMAR; 0.48±0.34, 0.38±0.29)before and at 6mo after surgery(P&#x003C;0.05), but there were no differences in corneal endothelial cells(2917.39±288.38 vs. 2959.19±336.27 cells/mm2, P=0.477). There were differences among Kmax, TCT, anterior surface K1 and K2 and posterior surface K1 before and after surgery(P&#x003C;0.05), and all increased at 1mo after surgery then returned to preoperative level at 3mo after surgery, while there was no difference in the posterior K2. Furthermore, there were statistical significance in A1T, HCPD and SP-A1 before and after surgery(P&#x003C;0.05), while there were no statistical significance in A1L, A1V,A2T, A2L, A2V, HCDA, HCR and bIOP(P&#x003E;0.05).CONCLUSION: Epithelial-off accelerated CXL can prevent the progression of keratoconus within half year after surgery, and it has certain safety.

The anatomical limit and strategies for molar movement during orthodontic treatment / 口腔疾病防治

@#In many cases, tooth movement over a considerable distance is needed to meet the major goal of orthodontic treatment, which has always been to correct malocclusion and improve the facial profile in patients with skeletal malocclusion. However, tooth movement over a considerable distance also carries risks of dehiscence, fenestration, root exposure, and so forth. The reason lies in neglecting many limits for tooth movement, especially anatomical characteristics. This review focuses on structural limits for orthodontic molar movement, such as the alveolar cortex, the maxillary sinus floor, and the mandibular canal. In addition, we set the strategy in clinical orthodontics. For the alveolar cortex and the mandibular canal, orthodontists are recommended to move the root away from the cortical bone initially and formulate personalized molar movement plans according to clinical examination and cone-beam computed tomography (CBCT) and other imaging examinations. First, the molar root was controlled by torque away from the bone plate, and then, the molar movement amount and direction were controlled according to the personalized movement path. In regard to the maxillary sinus floor, light and continuous forces and scientific biomechanics are suitable for bodily tooth movement. In summary, better therapeutic efficacy and long-term stabilization could be achieved by circumventing the limits and risks caused by anatomical limitations and characteristics.

Effect of Pin Holes Location of Unicompartmental Knee Arthroplasty on Postoperative Tibial Plateau Mechanical Properties / 中国医疗器械杂志

OBJECTIVE@#The purpose of this study is to explore the biomechanical characteristics of the tibia after unicompartmental knee arthroplasty with different distributions of two-pin holes, and to optimize the two-pin holes scheme to reduce the risk of tibial fractures after unicompartmental knee arthroplasty.@*METHODS@#Lower limbs model is segmented and reconstructed from computed tomography images. Four combinations of two pin holes created for tibial cutting guide placement are simulated with finite element analysis.@*RESULTS@#In the third mode, the positioning hole at the proximal medial edge of the tibial plateau has the highest stress value, and the position of the positioning hole near the medial edge of the proximal tibial plateau appears stress concentration.@*CONCLUSIONS@#The present study revealed that placing tibial cutting guide holding pins centrally would lower the risks of periprosthetic fracture of the medial tibial plateau.

Comparison of corneal biomechanics and levels of serum Leptin and extracellular superoxide dismutase in patients with non-proliferative diabetic retinopathy or proliferative diabetic retinopathy / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To explore the differences of corneal biomechanical parameters, serum Leptin and extracellular superoxide dismutase(ecSOD)levels in patients with non-proliferative diabetic retinopathy(NPDR)or proliferative diabetic retinopathy(PDR).METHODS: This article is a prospective study. A total of 118 patients with type 2 diabetes mellitus(T2DM)and diabetic retinopathy(DR)who were admitted to our hospital from May 2020 to May 2022 were selected, and they were divided into NPDR group(n=57)and PDR group(n=61)according to the degree of lesion. Another 54 patients with T2DM but no retinopathy and 52 healthy individuals were set as NDR group and control group. Then the differences in the corneal biomechanics measured with [central corneal thickness(CCT), intraocular pressure(IOP), spherical equivalent(SE), the first applanation time(A1T), the first applanation length(A1L), deformation amplitude(DA)] and serum Leptin and ecSOD levels were analyzed, and multivariate Logistic regression analysis was conducted to analyze the high-risk factors affecting the occurrence of PDR.RESULTS: The CCT, IOP and A1T in PDR and NPDR groups were higher than those in control and NDR groups, and DA was lower than those in control and NDR groups(all P&#x0026;#x003C;0.05), and the CCT, IOP and A1T in the PDR group were higher than those in the NPDR group(all P&#x0026;#x003C;0.05). The levels of serum Leptin and ecSOD in PDR group, NPDR group and NDR group were higher than those in the control group(all P&#x0026;#x003C;0.05). The course of DM, CCT, IOP, A1T, and serum Leptin and ecSOD levels between NPDR group and PDR group were statistically significant(all P&#x0026;#x003C;0.05). Multivariate Logistic regression analysis denoted that DM course, CCT, IOP, A1T, Leptin, and ecSOD are risk factors that affect the occurrence of PDR, while DA is a protective factor that affects the occurrence of PDR(all P&#x0026;#x003C;0.05). CONCLUSION: CCT, IOP and levels of serum Leptin and ecSOD in PDR patients were significantly increased compared to those in the NPDR patients, while DA was significantly reduced. Furthermore, CCT, IOP, A1T and levels of serum Leptin and ecSOD were risk factors affecting the occurrence of PDR, while DA was a protective factor affecting the occurrence of the PDR.

Changes in corneal biomechanics after small incision lenticule extraction and femtosecond laser-assisted laser in situ keratomileusis evaluated by corneal visualization Scheimpflug technology / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To evaluate the changes in corneal biomechanics of patients with moderate refractive error after receiving small-incision lenticule extraction(SMILE)and femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK)using the corneal visualization Scheimpflug technology(Corvis ST).METHODS:Prospective cohort study. A total of 65 moderate myopia patients(65 eyes)who were scheduled to undergo refractive surgery at the Ophthalmic Refractive Surgery Center of the Ningxia Eye Hospital from November 2020 to November 2021 were included in the study, and there were 30 eyes in the SMILE group and 35 eyes in the FS-LASIK group. The changes in corneal biomechanical parameters, including integrated radius(IR), inverse concave radius(ICR), deformation amplitude ratio 2mm(DAR2), stiffness parameter at first applanation(SP-A1), ambrosio relational thickness(ARTh)and the central curvature radius at highest concavity(HC-Radius)were observed by Corvis ST between both groups preoperatively and 1 and 3mo postoperatively.RESULTS: There were no statistical significance in biomechanical parameters between two groups of patients 1 and 3mo postoperatively(P&#x0026;#x003E;0.05). IR, ICR and DAR2 of each groups of patients 1 and 3mo postoperatively were significantly increased than those preoperatively, and SP-A1, ARTh and HC-Radius were significantly decreased than those preoperatively(all P&#x0026;#x003C;0.05). The biomechanical parameters at 1mo and 3mo postoperatively showed no statistical significance(P&#x0026;#x003E;0.05). In addition, a positive correlation was found between central corneal thickness(CCT)and ARTh and SP-A1 of the two groups of patients at 3mo postoperatively(FS-LASIK group: r=0.727, 0.819, SMLIE group: r=0.683, 0.434, all P&#x0026;#x003C;0.05), while a negative correlation was found between CCT and IR and ICR at 3mo postoperatively.(FS-LASIK group: r=-0.697, -0.622, SMLIE group: r=-0.447, -0.491, all P&#x0026;#x003C;0.05).CONCLUSION:For patients with moderate myopia, both SMILE and FS-LASIK can reduce corneal biomechanical stability. Both surgeries showed no significant differences in the effect on biomechanical, and the biomechanical has been stabilized at 1mo postoperatively. A correlation was found between postoperative CCT and ARTh, SP-A1, IR and ICR.

A Review on Finite Element Modelling and Simulation for Upper Limb of Human Bone and Implant

@#Medical implants are normally used in clinical practice to treat most orthopaedics situations involving bone fractures, deformities, dislocation, and lengthening. It should be noted that specific measures regarding biomechanical and biomaterial characteristics are required for a successful post-surgery procedure. Biomechanical evaluations on the medical implants could be performed by utilising computer and engineering technology. One of them is in silico studies using finite element method that could be simulated in high-performance computer. However, various assumptions are required in computer simulation, such as the constraints on data input and computer resources. This review paper discusses current approaches of constructing a finite element model of human bone with specific material properties for upper limb such as the shoulder joint, humerus, elbow joint, radius and wrist joint. Previous related literatures were reviewed from selected keywords and search engines. To narrow the literature search in this study, inclusion and exclusion criteria of the literature searching were applied. We looked at the current level of knowledge in this field and offered recommendations for future study. In conclusion, studies from previous literature have demonstrated several ways for developing mathematical models and simulating medical implants.