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.

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.

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.

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.

Application of a new type of simulated manikin based on the biomechanical characteristics of the simulated thoracic cavity in the teaching and training of cardiopulmonary resuscitation / 中华医学教育探索杂志

Objective:To simulate the biomechanical characteristics of the real human thoracic cavity with a multi-spring group variable damping structure, and to design a new cardiopulmonary resuscitation training manikin based on the simulated thoracic biomechanical characteristics combined with the original electronic feedback system, and to test its application effect in cardiopulmonary resuscitation (CPR) teaching.Methods:A total of 60 undergraduate students majoring in five-year clinical medicine of Batch 2019 in Naval Medical University were selected as the research objects and were randomly divided into the experimental group and the control group, with 30 students in each group. The control group used the traditional manikin for CPR training, and the experimental group used the new type of manikin for CPR training based on the control group. After the training, the two groups of personnel were assessed for single skill. The single skill was mainly manual CPR operations, including artificial respiration and chest compressions. The theory and skill operation assessment of CPR and satisfaction for teaching method in the two groups were compared. SPSS 23.0 was used for statistical analysis.Results:The students in the experimental group scored (54.33±3.09) points in the single skill operation assessment, which were significantly better than that of the students in the control group [(52.33±3.08) points], and the difference was statistically significant ( P<0.05). The follow-up questionnaire showed that the students in the experimental group had a better evaluation of the teaching and training effect of the new type of manikin. Conclusion:Compared with the traditional manikin, the new CPR manikin can simulate the CPR emergency scene of the real human body, which can effectively improve the CPR teaching effect of standardized training for medical students, and help the standardization, normalization, and popularization of CPR technology in China.

Progress in Biomechanics and Mechanobiology of Dendritic Cells / 医用生物力学

Dendritic cells (DCs) are now known as the most powerful antigen-presenting cells in vivo, with efficient antigen uptaking, and processing capabilities. They can present antigens to naïve T cells in secondary lymphoid tissues, thereby induce immune response or tolerance, and play a key role in initiating and amplifying innate and adaptive immunity. DCs experience complex chemical and mechanical microenvironment changes and show different mechanophenotypes and immunophenotypes in the process of exerting their physiological functions. Deeply understanding the chemical and mechanical factors that regulate the mechanophenotypes and immunophenotypes of DCs is a prerequisite for using DCs to treat immune related diseases. In this review, the progress in the biomechanics and mechanobiology research of DCs was mainly introduced, and their potential applications and future development directions in the treatment of immune related diseases were explored.

Advances in Cardiovascular Biomechanics and Mechanobiology Research in 2022 / 医用生物力学

The cardiovascular system plays a crucial role in the entire organism. It performs many important functions, such as providing organs and tissues with nutrients, hormones, delivering oxygen to cells, and maintaining physiological temperature. For a long time, accurately identifying the nonlinear and anisotropic mechanical properties of the vascular wall within the body has been regarded as a key challenge in cardiovascular biomechanics, as these properties are critical determinants of overall cardiac function. Currently, the roles of mechanical and tissue properties in cardiovascular diseases such as arterial aneurysms and atherosclerosis remain hot topics in both basic and clinical researches. This review aims to summarize the latest research advances in the field of cardiovascular biomechanics and mechanobiology in the year 2022. In terms of cardiovascular biomechanics, researchers focus on the structure, function, and pathophysiology of the cardiovascular system, and use experimental methods such as mechanical modeling to study these issues. These include studies about biomechanical properties of diseases such as atherosclerosis, arterial aneurysms, and myocardial infarction, as well as the development and testing of treatment methods based on dynamics of the cardiovascular system. In terms of mechanobiology, researchers explore mechanical properties of cardiovascular cells and extracellular matrix, including prediction of cell mechanical properties based on machine learning, studies of biological material mechanical properties, and the role of mechanical properties in cardiovascular cell phenotype changes. These research findings provide new ideas and methods for diagnosing and treating cardiovascular diseases and offer new insights into researches in biomechanics and mechanobiology fields.

Advances in Mechanotransduction Pathway of Macrophage / 医用生物力学

Mechanical stimulation in micro-environment ( such as matrix stiffness, surface topography, cyclical stretch) can be perceived by macrophages through receptors on cell membrane, transmitted to the nucleus along the adhesion protein molecular chain and cytoskeleton, and also converted into biochemical signal to stimulate gene transcription. Mechanical stimulation drives various biological functions in macrophages, such as adhesion, proliferation, migration, and polarization, thereby playing a corresponding role in disease progression and tissue regeneration. This study demonstrates the role of micro-environment mechanics in macrophages polarization and function, and elucidates the related mechanism of mechanotransduction pathway in macrophages, so as to provide molecular biomechanics insights into the development of macrophage-targeting immunomodulatorybiomaterials.

Progress in Biomechanical Study of Rotator Cuff Repair / 医用生物力学

The rotator cuff is an important structure to maintain movement and dynamic stability of the shoulder joint. Rotator cuff injury changes its unique biomechanical effects, resulting in shoulder pain and mobility disorders. Although great progress has been made in suture technology and fixation method, the rate of postoperative retear is still very high. Understanding the biomechanical mechanism of normal rotator cuff and restoring the special biomechanical effect of rotator cuff after injury are the key to prevent postoperative retear. This article reviewed biomechanical researches on rotator cuff repair in recent years, in order to provide some theoretical guidance for clinical operation.

Biomechanical Characteristics of Idiopathic Pulmonary Fibrosis / 医用生物力学

Idiopathic pulmonary fibrosis (IPF) is a common chronic interstitial fibrotic disease. During the fibrosis process, myofibroblasts are abnormally activated, collagen is deposited in large quantities and the biomechanical characteristics of lung tissue are significantly altered. In this paper, a systematic review about the changes in lung tissues, cellular biomechanical properties and biomechanical signals during the process of IPF was presented, and the in vitro reproduction of biomechanical features and therapeutic strategies for targeting biomechanics wassummarized, so as to provide references for clinical prevention and treatment of IPF.

Age-Related Changes of Biomechanical Properties for Limb Bones in Male Rats / 医用生物力学

Objective To investigate the age-related changes of biomechanical properties for humerus, femur and tibia in male rats and their application values in age estimation. Methods According to different weeks of age, 90 healthy male SD rats were divided into 2, 4, 6, 8, 17, 26, 52, 78 and 104-week groups with 10 rats in eachgroup. After the rats were executed by excessive anesthesia, humerus, femur, and tibia were separated and the attached soft tissues were removed. The length of the above-mentioned bones and the diameter of the middle section (compression site) were measured with vernier caliper, and the three-point bending test was conducted with electronic universal material testing machine to detect the ultimate load and displacement under ultimate load. Results There were significant differences in the ultimate load of humerus, femur and tibia among male rats in different age groups (P<0. 05). With the increase of week age, the ultimate loads of the humerus, femur and tibia increased first and then decreased, and reached the peak value in 52-week age group, showing a strong positive correlation with week age before 52 weeks ( r = 0. 884,0. 933,0. 929, P<0. 05). There was no significant difference in humerus and tibia. The displacement of femur under ultimate load was weakly positively correlated with week age (R= 0. 406,P<0. 05). The age prediction accuracy for automatic linear modeling of ultimate load for humerus, femur, tibia and three above-mentioned bones in rats before 52-week age was 78. 2% , 86. 8% , 84. 1% and 88. 3% , respectively. There was a strong positive correlation between the length of humerus, femur and tibia and the ultimate load (R= 0. 904, 0. 897, 0. 814, P<0. 05). The diameters of humerus, femur and tibia were strongly positively correlated with the ultimate load (R = 0. 759, 0. 814 and 0. 745, P<0. 05). Conclusions The ultimate loads of humerus, femur and tibia in male rats increased first and then decreased with age, and were positively correlated with age before 52 weeks, which could be used for age inference. The highest accuracy of age estimation was ultimate loads of three bones, followed by femur. The length/ middle diameter of humerus, femur and tibia were strongly positively correlated with the ultimate load.

Biomechanical Study on Different fixation Methods of Cannulated Screws for Posterior Malleolus Fracture / 医用生物力学

Objective To study biomechanical effects of cannulated screws at different fixation angles on posterior malleolus fracture based on finite element method, so as to determine the best fixation method of cannulatedscrew. Methods The finite element model of ankle joint, including tibia, fibula, astragalus, corresponding cartilage and ligaments was reconstructed using CT images, and 1 / 2 posterior malleolus fracture model was established on the basis of verifying its validity. The biomechanical effects of cannulated screw fixation on posterior malleolus fracture fixation model were analyzed. Results Compared with 0°,5°,10°,20° fixation model, the 15° fixation model had the smallest displacement. The screw stress of 15° fixation model was lower than that of 5°, 10°, 20° fixation model, and higher than that of 0° fixation model. But when the screw fixation angle was 0°, the peak contact pressure of ankle joint was much larger than that of normal ankle joint, which was easy to cause traumatic osteoarthritis. Conclusions Cannulated screw is safe and effective for treating posterior malleolus fracture which is less than 1 / 2 fragment size. The displacement and stress of the model are different at different fixation angles of screws. When the fixation angle of screw is 15°, the biomechanical stability is the best, which can be used to guide clinical operation.

The Action Effect of Two Kinds of Lumbar Massage Obliquity Manipulation with Different Lumbar Degeneration Degrees: A Comparative Study / 医用生物力学

Objective To compare the action effect of traditional and modified lumbar massage obliquity manipulation with different degrees of lumbar degeneration. Methods The biomechanical model of quality-spring-damping system lumbar spine was established and massage forces from professional massage doctors were collected. The force was used as input of the model, and lumbar degeneration was simulated by increasing elastic coefficient of the spring and damping coefficient of the damping in the model. By using MATLAB/ Simulink simulation technology, the effects of massage obliquity manipulation ( the maximum relative displacement and maximum acceleration) with different degrees of lumbar degeneration were obtained for comparative analysis.Results When the lumbar spine was degenerative, the maximum relative displacement and maximum acceleration of each segment were obtained under two manipulations. With the increase of lumbar degenerationdegree, the maximum relative displacement and maximum acceleration of each segment under two manipulations showed a downward trend, and the attenuation rate of the maximum relative displacement and maximum acceleration of each segment under two manipulations was obtained. Conclusions When degenerative changes in the spine do not occur, the effectiveness of traditional lumbar massage obliquity manipulation is slightly better than that of modified lumbar massage obliquity manipulation, but the safety of modified lumbar massage obliquity manipulation is obviously better than that of the traditional lumbar massage obliquity manipulation, so the modified lumbar massage obliquity manipulation should be used. With the aggravation of lumbar degeneration, the action effects of two manipulations are attenuated in a power function. The attenuation rate of effectiveness of modified lumbar massage obliquity manipulation is significantly faster than that of traditional lumbar massage obliquity manipulation, indicating that the modified lumbar massage obliquity manipulation should not be used in the caseof lumbar degeneration.