Biomechanical Effects of Angiotensin 1-7 in Diabetes Rats Femur / Efectos Biomecánicos de la Angiotensina 1-7 en el Fémur de Ratas Diabéticas

SUMMARY: It is known that diabetes mellitus has late complications, including microvascular and macrovascular diseases. Diabetes can affect bones through biochemical markers of bone structure, density, and turnover. This study aimed to biomechanically investigate the bone-protective effects of angiotensin 1-7 (Ang 1-7), one of the active peptides in the renin-angiotensin system, in rats with diabetes. Thirty male Wistar albino rats, three months old and weighing 250-300 g, were divided into four groups: diabetes, Ang 1- 7, diabetes plus Ang 1-7, and control. One month later, diabetes developed in rats; the rats were sacrificed, and their right femur was removed. Three-point bending biomechanical tests were performed on the femurs. The diabetic group had significantly higher bone fragility than the other groups (Pr >.05). Bone fragility was lower, and bone flexibility was higher in the Ang 1-7 groups (Pr>F value 0.05). As a result of our study, the effect of Ang 1-7 on the bones of rats with diabetes was investigated biomechanically. Ang 1-7 has a protective impact on the bones of rats with diabetes.

Se sabe que la diabetes mellitus tiene complicaciones tardías, incluyendo enfermedades microvasculares y macrovasculares. La diabetes puede afectar los huesos a través de los marcadores bioquímicos de la estructura, la densidad y el recambio óseo. Este estudio tuvo como objetivo investigar biomecánicamente los efectos protectores en los huesos de la angiotensina 1-7 (Ang 1-7), uno de los péptidos activos en el sistema renina-angiotensina, en ratas con diabetes. Treinta ratas albinas Wistar macho, de tres meses de edad y con un peso de 250-300 g, se dividieron en cuatro grupos: diabetes, Ang 1-7, diabetes más Ang 1-7 y control. Un mes después, se desarrolló diabetes en ratas; se sacrificaron los animales y se extrajo su fémur derecho. Se realizaron pruebas biomecánicas de flexión de tres puntos en los fémures. El grupo diabéticos tenía una fragilidad ósea significativamente mayor que los otros grupos (Pr > 0,05). La fragilidad ósea fue menor y la flexibilidad ósea fue mayor en los grupos Ang 1-7 (valor Pr>F 0,05). Como resultado de nuestro estudio, se determinó biomecánicamente el efecto de Ang 1-7 en los huesos de ratas con diabetes. Se concluye que Ang 1-7 tiene un impacto protector en los huesos de ratas diabéticas.

Biomechanical Gait Analysis in Patients with Osteonecrosis of the Femoral Head / Análise biomecánica da marcha de pacientes com osteonecrose da cabeça do fémur

Abstract Objectives Although osteonecrosis of the femoral head is a prevalent condition, its effects on gait parameters have not been thoroughly studied and are not well-established in the current literature. The primary aim of the present study is to describe gait in patients with a diagnosis of osteonecrosis. Methods This is a cross-sectional study. Nine patients diagnosed with osteonecrosis of the femoral head who were regularly followed-up at an outpatient clinic were selected for the present study and underwent gait analysis using Vicon Motion Capture Systems. Spatiotemporal data was obtained, and joint angles were calculated using an Euler angle coordinate system. Distal coordinate systems were used to calculate joint momentsand forceplatestoobtaingroundreactionforces. Results Patients with osteonecrosis presented with slower velocity (0.54 m/s ± 0.19) and smaller cadence (83.01 steps/min ± 13.23) than healthy patients. The pelvic obliquity range of motion was of 10.12° ± 3.03 and rotation was of 18.23° ± 9.17. The mean hip flexion was of 9.48° ± 3.40. Ground reaction forces showed reduced braking and propelling forces. Joint moments were reduced for flexion and adduction (0.42 Nm/kg ± 0.2 and 0.30 Nm/kg ± 0.11, respectively) but the abduction moment was increased (0.42 Nm/kg ± 0.18). Conclusions The present study showed that osteonecrosis of the femoral head presents compensatory gait mechanisms, with increased pelvic motion and decreased knee flexion to protect the hip joint. Decreased moments for hip flexion and adduction were also identified and muscle weakness for those groups may be correlated to the disease.

Resumo Objetivos Embora a osteonecrose da cabeça do fêmur seja uma lesão prevalente, seus efeitos sobre os parâmetros da marcha não foram minuciosamente estudados e não estão bem estabelecidos na literatura atual. O objetivo principal do presente estudo é descrever a marcha em pacientes com osteonecrose. Métodos Trata-se de um estudo transversal. Nove pacientes com diagnóstico de osteonecrose da cabeça do fêmur, sob acompanhamento regular em ambulatório, foram selecionados para o presente estudo e submetidos à análise da marcha com Vicon Motion Capture Systems. Os dados espaciais e temporais foram obtidos e os ângulos articulares foram calculados com o sistema de coordenadas angulares de Euler. Sistemas de coordenadas distais e plataformas de força foram utilizados para o cálculo de momentos articulares e de forças de reação ao solo, respectivamente. Resultados Os pacientes com osteonecrose apresentaram menor velocidade (0,54 m/s ± 0,19) e menor cadência (83,01 passos/minuto ± 13,23) do que pacientes saudáveis. As amplitudes de movimento de obliquidade e rotação pélvica foram de 10,12°± 3,03 e 18,23° ± 9,17, respectivamente. A média de flexão do quadril foi de 9,48° ± 3,40. O estudo das forças de reação ao solo revelou redução das forças de frenagem e propulsão. Os momentos articulares de flexão e adução caíram (0,42 Nm/kg ± 0,2 e 0,30 Nm/kg ± 0,11), mas o momento de abdução aumentou (0,42 Nm/kg ± 0,18). Conclusões O presente estudo mostrou que a osteonecrose da cabeça do fêmur é associada a mecanismos compensatórios da marcha, com aumento da movimentação pélvica e diminuição da flexão do joelho para proteção da articulação do quadril. A redução dos momentos de flexão e adução do quadril também foi identificada e a fraqueza destes grupos musculares pode estar correlacionada à doença.

Is there a Difference in Interfragmentary Compression Strength Between Fully or Partially Threaded Screws? Results of an Experimental Biomechanical Pilot Study / Há diferença na força de compressão interfragmentar entre parafusos com rosca total ou parcial? Resultados de um estudo biomecânico experimental piloto

Abstract Objective This study assessed differences between fully- and partially-threaded screws in the initial interfragmentary compression strength. Our hypothesis was that there would be an increased loss in initial compression strength with the partially-threaded screw. Methods A 45-degree oblique fracture line was created in artificial bone samples. The first group (FULL, n = 6) was fixed using a 3.5-mm fully-threaded lag screw, while the second group (PARTIAL, n = 6) used a 3.5-mm partially-threaded lag screw. Torsional stiffness for both rotational directions were evaluated. The groups were compared based on biomechanical parameters: angle-moment-stiffness, time-moment-stiffness, maximal torsional moment (failure load), and calibrated compression force based on pressure sensor measurement. Results After loss of one PARTIAL sample, no statistically significant differences in calibrated compression force measurement were observed between both groups: [median (interquartile range)] FULL: 112.6 (10.5) N versus PARTIAL: 106.9 (7.1) N, Mann-Whitney U-test: p = 0.8). In addition, after exclusion of 3 samples for mechanical testing (FULL n = 5, PARTIAL n = 4), no statistically significant differences were observed between FULL and PARTIAL constructs in angle-moment-stiffness, time-moment-stiffness, nor maximum torsional moment (failure load). Conclusion There is no apparent difference in the initial compression strength (compression force or construct stiffness or failure load) achieved using either fully-or partially-threaded screws in this biomechanical model in high-density artificial bone. Fully-threaded screws could, therefore, be more useful in diaphyseal fracture treatment. Further research on the impact in softer osteoporotic, or metaphyseal bone models, and to evaluate the clinical significance is required.

Resumo Objetivo Este estudo avaliou diferenças entre parafusos com rosca total ou parcial na resistência à compressão interfragmentar inicial. Nossa hipótese era de que haveria maior perda de resistência à compressão inicial com o parafuso de rosca parcial. Métodos Uma linha de fratura oblíqua de 45 graus foi criada em amostras de osso artificial. O primeiro grupo (TOTAL, n = 6) foi fixado com um parafuso de 3,5 mm de rosca total, enquanto o segundo grupo (PARCIAL, n = 6) usou um parafuso de 3,5 mm de rosca parcial. Avaliamos a rigidez à torção em ambas as direções de rotação. Os grupos foram comparados com base nos seguintes parâmetros biomecânicos: momento de rigidez-ângulo, momento de rigidez-tempo, momento de torção máxima (carga de falha) e força de compressão calibrada com base na medida do sensor de pressão. Resultados Depois da perda de uma amostra PARCIAL, não foram observadas diferenças estatisticamente significativas na força de compressão calibrada entre os 2 grupos [mediana (intervalo interquartil)]: TOTAL: 112,6 (10,5) N e PARCIAL: 106,9 (7,1) N, com p = 0,8 segundo o teste U de Mann-Whitney). Além disso, após a exclusão de 3 amostras para testes mecânicos (TOTAL, n = 5, PARCIAL, n = 4), não foram observadas diferenças estatisticamente significativas entre os construtos TOTAL e PARCIAL quanto ao momento de rigidez-ângulo, momento de rigidez-tempo ou momento de torção máxima (carga de falha). Conclusão Não há diferença aparente na força de compressão inicial (força de compressão ou rigidez do construto ou carga de falha) com o uso de parafusos de rosca total ou parcial neste modelo biomecânico em osso artificial de alta densidade. Parafusos de rosca total podem, portanto, ser mais úteis no tratamento de fraturas diafisárias. Mais pesquisas são necessárias sobre o impacto em modelos ósseos osteoporóticos ou metafisários de menor densidade e avaliação do significado clínico.

Monoaxial Mechanical Tests on Porcino Knee Ligaments / Ensaios mecânicos monoaxiais nos ligamentos do joelho porcino

Abstract The failure of ligament reconstruction has different risk factors, among which we can highlight the period before its incorporation, which is a mechanically vulnerable period. Loss of resistance over time is a characteristic of living tissues. Dissection with bone insertions of the cruciate ligaments of animal models is not described; however, it is essential for monoaxial assays to extract information from tests such as relaxation. The present work describes the dissection used for the generation of a test body for the performance of nondestructive tests to evaluate the mechanical behavior. We performed dissection of four porcino knee ligaments, proposing a dissection technique for the cruciate ligaments with bone inserts for comparison with collateral ligaments. The ligaments were submitted to relaxation tests and had strain gauges placed during the tests. The results showed viscoelastic behavior, validated by strain gauges and with a loss over time; with some ligaments presenting with losses of up to 20%, a factor to be considered in future studies. The present work dissected the four main ligaments of the knee demonstrating the posterior approach that allows maintaining their bone insertions and described the fixation for the monotonic uniaxial trials, besides being able to extract the viscoelastic behavior of the four ligaments of the knee, within the physiological limits of the knee.

Resumo A falha da reconstrução ligamentar tem diferentes fatores de risco, dentre os quais podemos destacar o período antes da sua incorporação, o qual configura um período mecânico vulnerável. A perda de resistência ao longo do tempo é uma característica dos tecidos vivos. A dissecção com as inserções ósseas dos ligamentos cruzados de modelos animais não é descrita; todavia, para os ensaios monoaxiais, é fundamental extrair as informações de ensaios como os de relaxação. O presente trabalho realiza a descrição da dissecção utilizada para a geração de corpo de prova para a realização de ensaios não destrutivos para avaliar o comportamento mecânico. Realizamos dissecção de quatro ligamentos de joelho porcino, propondo uma técnica de dissecção para os ligamentos cruzados com as inserções ósseas para comparação com os colaterais. Os ligamentos foram submetidos a testes de relaxação e foram colocadas strain gauges durante os testes. Os resultados mostraram comportamento viscoelástico, validado pelas strain gauges e com uma perda ao longo do tempo, sendo que, em alguns ligamentos, as perdas chegaram a até 20%, fator este a ser considerado em trabalhos futuros. O presente trabalho dissecou os quatro principais ligamentos do joelho, demonstrando a abordagem posterior que permite manter as suas inserções ósseas e descrevendo a fixação para os ensaios uniaxiais monotônicos, além de ter conseguido extrair o comportamento viscoelástico dos quatro ligamentos do joelho dentro dos limites fisiológicos do joelho.

Mechanical behavior of implant-supported full-arch prostheses in different locations in the maxilla: 3D-FEA and strain gauge analysis / Comportamento mecânico de próteses de arco inteiro implanto-suportadas em localizações diferentes na maxila: análise 3D-FEA e strain gauge

The maxillary bone restriction can limit the implants position to support a full-arch prosthesis. Objective:Therefore, this study evaluated the biomechanical behavior of a full-arch prosthesis supported by six implants in different configurations: group A (implants inserted in the region of canines, first premolars and second molars), group B (implants inserted in the region of first premolar, first molar and second molar) and group C (implants in second premolar, first premolar and second molar). Material and Methods: The models were analyzed by the finite element method validated by strain gauge. Three types of loads were applied: in the central incisors, first premolars and second molars, obtaining results of von-Mises stress peaks and microstrain. All registered results reported higher stress concentration in the prosthesis of all groups, with group C presenting higher values in all structures when compared to A and B groups. The highest mean microstrain was also observed in group C (288.8 ± 225.2 µÎµ/µÎµ), however, there was no statistically significant difference between the evaluated groups. In both groups, regardless of the magnitude and direction of the load, the maximum von-Mises stresses recorded for implants and prosthesis displacements were lower in group A. Conclusion: It was concluded that an equidistant distribution of implants favors biomechanical behavior of full-arch prostheses supported by implants; and the placement of posterior implants seems to be a viable alternative to rehabilitate totally edentulous individuals. (AU)

A limitação óssea maxilar totais pode limitar o posicionamento dos implantes para suportar uma prótese de arco total. Objetivo: Sendo assim, este estudo avaliou o comportamento biomecânico de uma prótese de arco total suportada por seis implantes em diferentes configurações: grupo A (implantes inseridos na região de caninos, primeiros pré-molares e segundos molares), grupo B (implantes inseridos na região de primeiro pré-molar, primeiro molar e segundo molar) e grupo C (implantes em segundo pré-molar, primeiro pré-molar e segundo molar). Materiais e métodos: Os modelos foram analisados pelo método de elementos finitos validados por extensometria. Foram aplicados três tipos de cargas: nos incisivos centrais, primeiros pré-molares e nos segundos molares, obtendo resultados de picos de tensão de von-Mises e microdeformação. Todos os resultados registrados mostraram maior concentração de tensão na prótese de todos os grupos, sendo que o grupo C apresentou maiores valores em todas as estruturas quando comparado com os grupos A e B. A maior média de microdeformação também foi observada no grupo C (288,8 ± 225,2 µÎµ/µÎµ), no entanto, não houve diferença estatisticamente significativa entre os grupos avaliados. Em todos os grupos, independentemente da magnitude e direção da carga, as tensões máximas de von-Mises registradas para os implantes e deslocamentos de próteses foram menores no grupo A. Conclusão: Concluiu-se que a distribuição de implantes de forma equidistante favorece o desempenho biomecânico das próteses de arco total suportada por implantes; e o posicionamento de implantes posteriores parece ser uma alternativa viável para reabilitar indivíduos densdentados totais. (AU)

Analysis of biomechanics in athletes with disabilities: a systematic and narrative review / Análise da biomecânica em atletas com deficiência: uma revisão sistemática e narrativa

Abstract Introduction Specifically in athletes with disabilities, investigations and biomechanical understanding seem to be even more relevant, as they provide data on how a certain type of disability limits sports practice and also describe parameters that allow the suggestion of relevant adaptations capable of guaranteeing a higher level comfort to practitioners. Objective To describe patterns of biomechanical behavior during exercise in athletes with disabilities, and to discuss possible relationships between the type of disability and the sport practiced. Methods This study performed a search in five electronic databases from the oldest records available until July 2020 using a search strategy that combined terms related to "athletes with disabilities" and "biomechanical analysis." Inclusion criteria: population (amateur or professional athletes with disabilities), intervention (sports practice), study design (observational), outcome (having evaluated biomechanics during sports practice). The biomechanical variables of interest included kinematic, kinetic, or electromyographic outcome measures. Results Tewnty-six articles met the inclusion criteria (n = 705 participants). Biomechanical analysis showed that there is a greater inclination in the angle of the head and an increase in the kinematic variables in blind athletes, which result in less distance, speed, and performance; compensatory body patterns, reduced mooring strength, speed, joint amplitude, and reduced final performance are observed in amputated limbs of amputees; and there was a strong correlation between the subject's functional classification and kinematic parameters in wheelchair athletes, with this being proportional to the level of impairment. Conclusion The outcomes demonstrated that the type of disability and the level of functional limitation are proportionally related to biomechanics in athletes with disabilities.

Resumo Introdução Em atletas com deficiência, as investigações e o entendimento biomecânico parecem ser ainda mais relevantes ao fornecer dados sobre de que modo determinado tipo de deficiência limita a prática esportiva e, ainda, descrever parâmetros que permitam sugestão de adaptações pertinentes capazes de garantir maior nível de conforto aos praticantes. Objetivo Descrever padrões de comportamento biomecânico durante o exercício em atletas com deficiência e discutir possíveis relações entre o tipo de deficiência e o esporte praticado. Métodos Este estudo realizou uma busca em cinco bases de dados eletrônicas a partir dos registros mais antigos disponíveis até julho de 2020, utilizando uma estratégia de busca que combinou termos relacionados a "atletas com deficiência" e "análise biomecânica". Critérios de inclusão: população (atletas amadores ou profissionais com deficiência), intervenção (prática esportiva), desenho do estudo (observacional), resultado (ter avaliado a biomecânica durante a prática esportiva). As variáveis biomecânicas de interesse incluíram medidas de desfecho cinemáticas, cinéticas ou eletromiográficas. Resultados Vinte e seis estudos atenderam aos critérios de inclusão (n = 705 participantes). Os resultados mostraram que há maior inclinação do ângulo da cabeça e aumento das variáveis cinemáticas em atletas cegos, resultando em menor distância, velocidade e desempenho; padrões corporais compensatórios, redução da força de amarração, velocidade, amplitude articular e desempenho final reduzido são observados em membros amputados de amputados; e parece haver relação entre a classificação funcional do sujeito e os parâmetros cinemáticos em atletas de cadeira de rodas, sendo esta proporcional ao grau de comprometimento. Conclusão Os resultados demonstraram que o tipo de deficiência e o nível de limitação funcional estão proporcionalmente relacionados à biomecâ-nica em atletas com deficiência.

Biomechanics of implant-supported restorations / Biomecânica das restaurações implantossuportadas

The rehabilitation of patients with dental implant-supported restorations is an ideal treatment option in contemporary dentistry. The aim of this review was to compile and to demonstrate the mechanical response during loading condition, on the stress distributions of implant-supported prostheses. The findings show that the majority of stresses were concentrated in the cervical region of the implant/abutment interface and that they can be affected by several clinical parameters and loading conditions. Finally, the final prosthetic design should combine superior mechanical response, long-term survival rate and allow patient satisfaction. (AU)

A reabilitação de pacientes com restaurações implanto-suportadas é uma opção de tratamento ideal na odontologia contemporânea. O objetivo desta revisão foi compilar e demonstrar a resposta mecânica durante a aplicação de carga, na distribuição de tensão de próteses implanto-suportadas. Os achados mostram que a maioria das tensões se concentram na região cervical da interface implante/pilar e pode ser afetada por diversos parâmetros clínicos e condições de carregamento. Por fim, o desenho protético final deve combinar uma melhor resposta mecânica, taxa de sobrevida a longo prazo e permitir a satisfação do paciente. (AU)

Investigation of tactile gait parameters based on deep learning of energy consumption estimation algorithm in sport / Investigação sobre parâmetros tácteis de marcha baseados no aprendizado profundo do algoritmo de estimativa de consumo energético no esporte / Investigación sobre los parámetros táctiles de marcha basados en el aprendizaje profundo del algoritmo de estimación del consumo de energía en el deporte

ABSTRACT Introduction In medicine, Deep Learning is a type of machine learning that aims to train computers to perform human tasks by simulating the human brain. Gait recognition and gait motion simulation is one of the most interesting research areas in the field of biometrics and can benefit from this technological feature. Objective To use Deep Learning to format and validate according to the dynamic characteristics of gait. Methods Gait was used for identity recognition, and gait recognition based on kinematics and dynamic gait parameters was performed through pattern recognition, including the position and the intensity value of maximum pressure points, pressure center point, and pressure ratio. Results The investigation shows that the energy consumption of gait as modeled analyzed, and the model of gait energy consumption can be obtained, which is comprehensively affected by motion parameters and individual feature parameters. Conclusion Real-time energy measurement is obtained when most people walk. The research shows that the gait frequency and body parameters obtained from the tactile parameters of gait biomechanics can more accurately estimate the energy metabolism of exercise and obtain the metabolic formula of exercise. There is a good application prospect for assessing energy metabolism through the tactile parameters of gait. Level of evidence II; Therapeutic studies - investigating treatment outcomes.

RESUMO Introdução Na medicina, o aprendizado profundo é um tipo de aprendizado de máquina que visa treinar computadores para a realização de tarefas humanas simulando o cérebro humano. O reconhecimento da marcha e a simulação do movimento de marcha são um dos pontos de maior interesse da investigação no campo da biometria e pode ser beneficiado com esse recurso tecnológico. Objetivo Utilizar o aprendizado profundo para formatar e validar, de acordo com as características dinâmicas da marcha. Métodos A marcha foi utilizada para o reconhecimento da identidade, e o reconhecimento da marcha baseado na cinemática e parâmetros dinâmicos de marcha foi realizado através do reconhecimento de padrões, incluindo a posição e o valor de intensidade dos pontos de pressão máxima, ponto central de pressão e relação de pressão. Resultados A investigação mostra que o consumo de energia da marcha como modelado analisado, e o modelo de consumo de energia da marcha pode ser obtido, o qual é afetado de forma abrangente pelos parâmetros de movimento e pelos parâmetros de características individuais. Conclusão A medição de energia em tempo real é obtida quando a maioria das pessoas caminha. A investigação mostra que a frequência da marcha e os parâmetros corporais obtidos a partir dos parâmetros tácteis da biomecânica da marcha podem estimar com maior precisão o metabolismo energético do exercício e obter a fórmula metabólica do exercício. Há uma boa perspectiva de aplicação para avaliar o metabolismo energético através dos parâmetros tácteis da marcha. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción En medicina, el aprendizaje profundo es un tipo de aprendizaje que pretende entrenar a los ordenadores para que realicen tareas humanas simulando el cerebro humano. El reconocimiento de la marcha y la simulación de su movimiento es uno de los puntos más interesantes de la investigación en el campo de la biometría y puede beneficiarse de este recurso tecnológico. Objetivo Utilizar el aprendizaje profundo para formatear y validar según las características dinámicas de la marcha. Métodos Se utilizó la marcha para el reconocimiento de la identidad, y el reconocimiento de la marcha basado en la cinemática y los parámetros dinámicos de la marcha se realizó mediante el reconocimiento de patrones, incluyendo la posición y el valor de la intensidad de los puntos de presión máxima, el punto de presión central y la relación de presión. Resultados La investigación muestra que el consumo de energía de la marcha, tal y como se analizó, y el modelo de consumo de energía de la marcha se puede obtener, que es ampliamente afectado por los parámetros de movimiento y los parámetros de las características individuales. Conclusión La medición de la energía en tiempo real se obtiene cuando la mayoría de la gente camina. La investigación muestra que la frecuencia de la marcha y los parámetros corporales obtenidos a partir de los parámetros táctiles de la biomecánica de la marcha pueden estimar con mayor precisión el metabolismo energético del ejercicio y obtener la fórmula metabólica del mismo. Existe una buena perspectiva de aplicación para evaluar el metabolismo energético a través de los parámetros táctiles de la marcha. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Study on the correlation between early three-dimensional gait analysis and clinical efficacy after robot-assisted total knee arthroplasty / 中华创伤杂志(英文版)

PURPOSE@#Robot-assisted technology is a forefront of surgical innovation that improves the accuracy of total knee arthroplasty (TKA). But whether the accuracy of surgery can improve the clinical efficacy still needs further research. The purpose of this study is to perform three-dimensional (3D) analysis in the early postoperative period of patients who received robot-assisted total knee arthroplasty (RATKA), and to study the trend of changes in gait parameters after RATKA and the correlation with the early clinical efficacy.@*METHODS@#Patients who received RATKA in the Center of Joint Surgery, the First Hospital Affiliated to Army Military Medical University from October 2020 to January 2021 were included. The imaging parameters, i.e., hip-knee-ankle angle, lateral distal femoral angle, medial proximal tibial angle, posterior condylar angle were measured 3 months post-TKA. The 3D gait analysis and clinical efficacy by Western Ontario Mac Master University Index (WOMAC) score were performed pre-TKA, 3 and 6 months post-TKA. The differences in spatiotemporal parameters of gait, kinetic parameters, and kinematic parameters of the operated limb and the contralateral limb were compared. The correlation between gait parameters and WOMAC scores was analyzed. Paired sample t-test and Wilcoxon rank-sum test were used to analyze the difference between groups, and Spearman correlation coefficient was used to analyze the correlation.@*RESULTS@#There were 31 patients included in this study, and the imaging indexes showed that all of them returned to normal post-TKA. The WOMAC score at 3 months post-TKA was significantly lower than that pre-TKA, and there was no significant difference between at 3 and 6 months. The 3D gait analysis results showed that the double support time of the operated limb reduced at 3 and 6 months (all p < 0.05), the maximum extension and maximum external rotation of the knee joint increased at stance phase, and the maximum flexion angle, the range of motion and the maximum external rotation increased at swing phase. Compared with the preoperative data, there were significant improvements (all p < 0.05). Compared with the contralateral knee joint, the maximum external rotation of the knee joint at swing phase was smaller than that of the contralateral side, and the maximum flexion and extension moment was greater than that of the contralateral knee. The maximum external rotation moment of the joint was greater than that of the contralateral knee joint (p < 0.05). There was a negative correlation between the single support time pre-TKA and the WOMAC score at 3 months (p = 0.017), and the single support time at 3 months was negatively correlated with the WOMAC score at 6 months (p = 0.043). The cadence at 6 months was negatively correlated with the WOMAC score at 6 months (p = 0.031). The maximum knee extension at stance phase at 6 months was negatively correlated with the WOMAC score at 6 month (p = 0.048). The maximum external rotation at stance phase at 6 months was negatively correlated with the WOMAC score at 6 months (p = 0.024).@*CONCLUSION@#The 3D gait analysis of RATKA patients is more sensitive than WOMAC score in evaluating the clinical efficacy. Trend of changes in gait parameters shows that the knee joint support, flexion and extension function, range of motion, external rotation and varus deformity moment of the patient were significantly improved at 3 months after surgery, and continued to 6 months after surgery. Compared with the contralateral knee, the gait parameters of the operated limb still has significant gaps in functionality, such as the external rotation and flexion and extension. The single support time, cadence, knee extension, and knee external rotation of the operated limb have a greater correlation with the postoperative WOMAC score. Postoperative rehabilitation exercises should be emphasized, which is of great value for improving the early efficacy of RATKA.

Finite element analysis of PMMA bone cement reinforced screw plate fixation for osteoporotic proximal humeral fracture / 中国骨伤

OBJECTIVE@#With the help of finite element analysis, to explore the effect of proximal humeral bone cement enhanced screw plate fixation on the stability of internal fixation of osteoporotic proximal humeral fracture.@*METHODS@#The digital model of unstable proximal humeral fracture with metaphyseal bone defect was made, and the finite element models of proximal humeral fracture bone cement enhanced screw plate fixation and common screw plate fixation were established respectively. The stress of cancellous bone around the screw, the overall stiffness, the maximum stress of the plate and the maximum stress of the screw were analyzed.@*RESULTS@#The maximum stresses of cancellous bone around 6 screws at the head of proximal humeral with bone cement enhanced screw plate fixation were 1.07 MPa for No.1 nail, 0.43 MPa for No.2 nail, 1.16 MPa for No.3 nail, 0.34 MPa for No.4 nail, 1.99 MPa for No.5 nail and 1.57 MPa for No.6 nail. These with common screw plate fixation were:2.68 MPa for No.1 nail, 0.67 MPa for No.2 nail, 4.37 MPa for No.3 nail, 0.75 MPa for No.4 nail, 3.30 MPa for No.5 nail and 2.47 MPa for No.6 nail. Overall stiffness of the two models is 448 N/mm for bone cement structure and 434 N/mm for common structure. The maximum stress of plate appears in the joint hole:701MPa for bone cement structure and 42 0MPa for common structure. The maximum stress of screws appeared at the tail end of No.4 nail:284 MPa for bone cement structure and 240.8 MPa for common structure.@*CONCLUSION@#Through finite element analysis, it is proved that the proximal humerus bone cement enhanced screw plate fixation of osteoporotic proximal humeral fracture can effectively reduce the stress of cancellous bone around the screw and enhance the initial stability after fracture operation, thus preventing from penetrating out and humeral head collapsing.

Biomechanical analysis of four internal fixations for Pauwels Ⅲ femoral neck fractures with defects / 中国骨伤

OBJECTIVE@#To investigate the biomechanical characteristics of different internal fixations for Pauwels type Ⅲ femoral neck fracture with defect, and provide reference for the treatment of femoral neck fracture.@*METHODS@#Three-dimensional (3D) finite element models of femoral neck fractures were established based on CT images, including fracture and fracture with defects. Four internal fixations were simulated, namely, inverted cannulated screw(ICS), ICS combined with medial buttress plate, the femoral neck system (FNS) and FNS combined with medial buttress plate. The von Mises stress, model stiffness and fracture displacements of fracture models under 2 100 N axial loads were measured and compared.@*RESULTS@#When femoral neck fracture was fixed by ICS and FNS, the peak stress was mainly concentrated on the surface of the screw near the fracture line, and the peak stress of FNS is higher than that of ICS;When the medial buttress plate was combined, the peak stress was increased and transferred to medial buttress plate, with more obvious of ICS fixation. For the same fracture model, the stiffness of FNS was higher than that of ICS. Compared with femoral neck fracture with defects, fracture model showed higher stiffness in the same internal fixation. The use of medial buttress plate increased model stiffness, but ICS increased more than FNS. The fracture displacement of ICS model exceeded that of FNS.@*CONCLUSION@#For Pauwels type Ⅲ femoral neck fracture with defects, FNS had better biomechanical properties than ICS. ICS combined with medial buttress plate can better enhance fixation stability and non-locking plate is recommended. FNS had the capability of shear resistance and needn't combine with medial buttress plate.

Biomechanical characteristics of retinaculum in the treatment of femoral neck fractures / 中国骨伤

OBJECTIVE@#To investigate the biomechanical characteristics of retinaculum in the treatment of femoral neck fractures.@*METHODS@#The CT data of a 75-year-old female volunteer was processed by software to construct an intact femur model and femoral neck fracture model fixed with three cannulated screws, which were divided into models with retinaculum or not. The Von-Mises stress distribution and displacement were compared to analyze the stability differences between the different models to study the mechanical characteristics of the retinaculum in the treatment of femoral neck fractures.@*RESULTS@#In the intact femur, the most obvious displacement appeared in the weight-bearing area of the femoral head, with retinaculum 0.381 37 mm, and without retinaculum 0.381 68 mm. The most concentrated part of the Von-Mises stress distribution was located in the medial and inferior part of the femoral neck, with retinaculum 11.80 MPa, without retinaculum 11.91 MPa. In the femoral neck fracture fixed with three cannulated screws model, the most obvious position of displacement also appeared in the weight-bearing area of the femoral head, with retinaculum 0.457 27 mm, without retinaculum 0.458 63 mm. The most concentrated part of the Von-Mises located at the medical and inferior part of the femoral neck, with retinaculum 59.22 MPa, without retinaculum 59.14 MPa. For the cannulated screws, the Von-Mises force peaks all appeared in the posterior and superior screw, with retinaculum 107.48 MPa, without retinaculum 110.84 MPa. Among the three screws, the Von-Mises stress of the anterior-superior screw was the smallest, which was 67.88 MPa vs 68.76 MPa in the retinaculum and non-retinaculum groups, respectively.@*CONCLUSION@#The complete retinaculum has little effect on the stability of intact femur and femoral neck fractures with anatomical reduction after internal fixation, and cannot effectively improve the stability of the fracture end after the fracture.

Research progress of lower limb muscle strength training in the treatment of lliotibial band syndrome / 中国骨伤

Iliotibial band syndrome (ITBS), as an overused injury of the lower extremities, has developed into a common cause of lateral knee pain. At present, the treatment of ITBS includes drug therapy, muscle strength training, physical therapy, and surgical treatment. Among these methods, physical therapy, drug therapy, and surgical treatment can only alleviate the symptoms of patients. As a safe and effective treatment, lower limb muscle strength training can improve patients' muscle strength, correct abnormal gait, and reduce the recurrence rate of the disease by paying attention to the dynamic changes of patients' recovery process. At present, the pathogenesis of ITBS remains unclear, and the treatment methods are not unified. It is necessary to further study the biomechanical factors related to the lower extremities and develop more scientific and comprehensive muscle strength training methods.

Analysis of Revision Content and Evaluation Attentions on Guidance for Registration of Metallic Bone Plate Internal Fixation System (Revised in 2021) / 中国医疗器械杂志

This study briefly introduces the revised content of Guidance for Registration of Metallic Bone Plate Internal Fixation System (Revised in 2021) compared to the original guidance, mainly including the principles of dividing registration unit, main performance indicators of standard specification, physical and mechanical performance research, and clinical evaluation. At the same time, in order to provide some references for the registration of metallic bone plate internal fixation system, this study analyzes the main concerns in the review process of these products based on the accumulation of experience combining with the current review requirements.

Study of Typical Functional Failure and Mechanical Properties of Non-absorbable Suture Anchor / 中国医疗器械杂志

OBJECTIVE@#To study the mechanical properties related to the typical functional failure modes of non-absorbable suture anchor in clinical use, and to support product design, development and verification.@*METHODS@#By retrieving the database of relevant adverse events, the typical functional failure modes of non-absorbable suture anchor were summarized, and the influencing factors of functional failure were further analyzed by studying the mechanical properties related to functional failure. The publicly available test data was retrieved for verification and provided reference for the researchers.@*RESULTS@#The typical functional failure modes of non-absorbable suture anchor include anchor failure, suture failure, fix loosening, inserter failure, which are related to the mechanical properties of products, such as screw-in torque and break torque of screw-in anchors, insertion force of knock-in anchors, suture strength, pull-out force before and after system fatigue test and elongation of sutures after fatigue test.@*CONCLUSIONS@#Enterprises should pay attention to improving the mechanical performance level of products through material, structural design and the suture weaving process to ensure the safety and effectiveness of products.

Development and global validation of a 1-week-old piglet head finite element model for impact simulations / 中华创伤杂志(英文版)

PURPOSE@#Child head injury under impact scenarios (e.g. falls, vehicle crashes, etc.) is an important topic in the field of injury biomechanics. The head of piglet was commonly used as the surrogate to investigate the biomechanical response and mechanisms of pediatric head injuries because of the similar cellular structures and material properties. However, up to date, piglet head models with accurate geometry and material properties, which have been validated by impact experiments, are seldom. We aim to develop such a model for future research.@*METHODS@#In this study, first, the detailed anatomical structures of the piglet head, including the skull, suture, brain, pia mater, dura mater, cerebrospinal fluid, scalp and soft tissue, were constructed based on CT scans. Then, a structured butterfly method was adopted to mesh the complex geometries of the piglet head to generate high-quality elements and each component was assigned corresponding constitutive material models. Finally, the guided drop tower tests were conducted and the force-time histories were ectracted to validate the piglet head finite element model.@*RESULTS@#Simulations were conducted on the developed finite element model under impact conditions and the simulation results were compared with the experimental data from the guided drop tower tests and the published literature. The average peak force and duration of the guide drop tower test were similar to that of the simulation, with an error below 10%. The inaccuracy was below 20%. The average peak force and duration reported in the literature were comparable to those of the simulation, with the exception of the duration for an impact energy of 11 J. The results showed that the model was capable to capture the response of the pig head.@*CONCLUSION@#This study can provide an effective tool for investigating child head injury mechanisms and protection strategies under impact loading conditions.

Research progress of optical motion capture technology in shoulder biomechanics / 中国骨伤

The shoulder joint is the most flexible joint in the body with the largest range of motion, and the movement pattern is more complex. Accurate capture of three-dimensional motion data of the shoulder joint is crucial for biomechanical evaluation. Optical motion capture systems offer a non-invasive and radiation-free method to capture shoulder joint motion data during complex movements, enabling further biomechanical analysis of the shoulder joint. This review provides a comprehensive overview of optical motion capture technology in the context of shoulder joint movement, including measurement principles, data processing methods to reduce artifacts from skin and soft tissues, factors influencing measurement results, and applications in shoulder joint disorders.

Three-dimensional finite element model construction and biomechanical analysis of customized titanium alloy lunate prosthesis / 中国修复重建外科杂志

OBJECTIVE@#To design customized titanium alloy lunate prosthesis, construct three-dimensional finite element model of wrist joint before and after replacement by finite element analysis, and observe the biomechanical changes of wrist joint after replacement, providing biomechanical basis for clinical application of prosthesis.@*METHODS@#One fresh frozen human forearm was collected, and the maximum range of motions in flexion, extension, ulnar deviation, and radialis deviation tested by cortex motion capture system were 48.42°, 38.04°, 35.68°, and 26.41°, respectively. The wrist joint data was obtained by CT scan and imported into Mimics21.0 software and Magics21.0 software to construct a wrist joint three-dimensional model and design customized titanium alloy lunate prosthesis. Then Geomagic Studio 2017 software and Solidworks 2017 software were used to construct the three-dimensional finite element models of a normal wrist joint (normal model) and a wrist joint with lunate prosthesis after replacement (replacement model). The stress distribution and deformation of the wrist joint before and after replacement were analyzed for flexion at and 15°, 30°, 48.42°, extension at 15°, 30°, and 38.04°, ulnar deviation at 10°, 20°, and 35.68°, and radial deviation at 5°, 15°, and 26.41° by the ANSYS 17.0 finite element analysis software. And the stress distribution of lunate bone and lunate prosthesis were also observed.@*RESULTS@#The three-dimensional finite element models of wrist joint before and after replacement were successfully constructed. At different range of motion of flexion, extension, ulnar deviation, and radial deviation, there were some differences in the number of nodes and units in the grid models. In the four directions of flexion, extension, ulnar deviation, and radial deviation, the maximum deformation of wrist joint in normal model and replacement model occurred in the radial side, and the values increased gradually with the increase of the range of motion. The maximum stress of the wrist joint increased gradually with the increase of the range of motion, and at maximum range of motion, the stress was concentrated on the proximal radius, showing an overall trend of moving from the radial wrist to the proximal radius. The maximum stress of normal lunate bone increased gradually with the increase of range of motion in different directions, and the stress position also changed. The maximum stress of lunate prosthesis was concentrated on the ulnar side of the prosthesis, which increased gradually with the increase of the range of motion in flexion, and decreased gradually with the increase of the range of motion in extension, ulnar deviation, and radialis deviation. The stress on prosthesis increased significantly when compared with that on normal lunate bone.@*CONCLUSION@#The customized titanium alloy lunate prosthesis does not change the wrist joint load transfer mode, which provided data support for the clinical application of the prosthesis.

Biomechanical effects of three internal fixation modes on femoral subtrochanteric spiral fractures in osteoporotic patients by finite element analysis / 中国修复重建外科杂志

OBJECTIVE@#The biomechanical characteristics of three internal fixation modes for femoral subtrochanteric spiral fracture in osteoporotic patients were compared and analyzed by finite element technology, so as to provide the basis for the optimization of fixation methods for femoral subtrochanteric spiral fracture.@*METHODS@#Ten female patients with osteoporosis and femoral subtrochanteric spiral fractures caused by trauma, aged 65-75 years old, with a height of 160-170 cm and a body weight mass of 60-70 kg, were selected as the study subjects. The femur was scanned by spiral CT and a three-dimensional model of the femur was established by digital technology. The computer aided design models of proximal intramedullary nail (PFN), proximal femoral locking plate (PFLP), and the combination of the two (PFLP+PFN) were constructed under the condition of subtrochanteric fracture. Then the same load of 500 N was applied to the femoral head, and the stress distribution of the internal fixators, the stress distribution of the femur, and the displacement of femur after fracture fixation were compared and analyzed under the three finite element internal fixation modes, so as to evaluate the fixation effect.@*RESULTS@#In the PFLP fixation mode, the stress of the plate was mainly concentrated in the main screw channel, the stresses of the different part of the plate were not equal, and gradually decreased from the head to the tail. In the PFN fixation mode, the stress was concentrated in the upper part of the lateral middle segment. In the PFLP+PFN fixation mode, the maximum stress appeared between the first and the second screws in the lower segment, and the maximum stress appeared in the lateral part of the middle segment of the PFN. The maximum stress of PFLP+PFN fixation mode was significantly higher than that of PFLP fixation mode, but significantly lower than that of PFN fixation mode ( P<0.05). In PFLP and PFN fixation modes, the maximum stress of femur appeared in the medial and lateral cortical bone of the middle femur and the lower side of the lowest screw. In PFLP+PFN fixation mode, the stress of femur concentrated in the medial and lateral of the middle femur. There was no significant difference in the maximum stress of femur among the three finite element fixation modes ( P>0.05). The maximum displacement occurred at the femoral head after three finite element fixation modes were used to fix subtrochanteric femoral fractures. The maximum displacement of femur in PFLP fixation mode was the largest, followed by PFN, and PFLP+PFN was the minimum, with significant differences ( P<0.05).@*CONCLUSION@#Under static loading conditions, the PFLP+PFN fixation mode produces the smallest maximum displacement when compared with the single PFN and PFLP fixation modes, but its maximum plate stress is greater than the single PFN and PFLP fixation mode, suggesting that the combination mode has higher stability, but the plate load is greater, and the possibility of fixation failure is higher.

Three-dimensional kinematic analysis of knee joint after anterior cruciate ligament reconstruction with personalized femoral positioner based on apex of deep cartilage / 中国修复重建外科杂志

OBJECTIVE@#To investigate the changes of knee joint kinematics after anterior cruciate ligament (ACL) reconstruction assisted by personalized femoral positioner based on the apex of deep cartilage (ADC).@*METHODS@#Between January 2021 and January 2022, a total of 40 patients with initial ACL rupture who met the selection criteria were randomly divided into the study group (using the personalized femoral positioner based on ADC design to assist ACL reconstruction) and the control group (not using the personalized femoral positioner to assist ACL reconstruction), with 20 patients in each group. Another 20 volunteers with normal knee were collected as a healthy group. There was no significant difference in gender, age, body mass index, and affected side between groups ( P>0.05). Gait analysis was performed at 3, 6, and 12 months after operation using Opti _ Knee three-dimensional knee joint motion measurement and analysis system, and the 6 degrees of freedom (flexion and extension angle, varus and valgus angle, internal and external rotation angle, anteroposterior displacement, superior and inferior displacement, internal and external displacement) and motion cycle (maximum step length, minimum step length, and step frequency) of the knee joint were recorded. The patients' data was compared to the data of healthy group.@*RESULTS@#In the healthy group, the flexion and extension angle was (57.80±3.45)°, the varus and valgus angle was (10.54±1.05)°, the internal and external rotation angle was (13.02±1.66)°, and the anteroposterior displacement was (1.44±0.39) cm, the superior and inferior displacement was (0.86±0.20) cm, and the internal and external displacement was (1.38±0.39) cm. The maximum step length was (51.24±1.29) cm, the minimum step length was (45.69±2.28) cm, and the step frequency was (12.45±0.47) step/minute. Compared with the healthy group, the flexion and extension angles and internal and external rotation angles of the patients in the study group and the control group decreased at 3 months after operation, and the flexion and extension angles of the patients in the control group decreased at 6 months after operation, and the differences were significant ( P<0.05); there was no significant difference in the other time points and other indicators when compared with healthy group ( P>0.05). In the study group, the flexion and extension angles and internal and external rotation angles at 6 and 12 months after operation were significantly greater than those at 3 months after operation ( P<0.05), while there was no significant difference in the other indicators at other time points ( P>0.05). There was a significant difference in flexion and extension angle between the study group and the control group at 6 months after operation ( P<0.05), but there was no significant difference of the indicators between the two groups at other time points ( P>0.05).@*CONCLUSION@#Compared with conventional surgery, ACL reconstruction assisted by personalized femoral positioner based on ADC design can help patients achieve more satisfactory early postoperative kinematic results, and three-dimensional kinematic analysis can more objectively and dynamically evaluate the postoperative recovery of knee joint.