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)

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.

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.

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.

Gait analysis of a patient with severe motor impairment post- intensive care due to COVID-19: 1 year follow up and physical therapy / Análise da marcha de paciente com comprometimento motor grave após terapia intensiva por COVID-19: acompanhamento de 1 ano e fisioterapia

Abstract Introduction Viral infections, such as infection by SARS-CoV-2, can affect gait biomechanics, but this effect can be overlapped by consequences of critical illness and time in intensive care unit. Objective To report biomechanical alterations during the clinical evolution of a post-COVID-19 patient who presented severe motor impairment after intensive care. Methods Data was collected from the patient's chart at José Silveira Foundation and previous medical reports from the hospitalization period. The patient was wheelchair bound, with physiotherapy twice a week, and by the end of 1-year follow-up was able to walk independently. Three-dimensional gait analysis with kinetics and electromyography were conducted at three time points. Results All spatiotemporal gait parameters, kinematic, kinetic and electromyographic data was importantly altered when compared to the normal range of values. With physiotherapy, gait quality indicators showed important improvements and all muscles presented a significant increase in the magnitude of the electromyographic signal (at least a two-fold increase). Trunk kinematic alterations decreased significantly during this period. Kinetic and kinematic changes perceived in the hips, knees and ankles showed approximation to the expected pattern, however still without normalizing, and patient's muscle coordination improved over time. Conclusion This report has great clinical importance, as it describes, using an instrumented gait laboratory, the evolution of a patient with severe motor impairment post intensive care due to COVID-19, a condition in lack of description in the literature, which will help health professionals in the planning of rehabilitation strategies.

Resumo Introdução Infecções virais, como a infecção por SARS-CoV-2, podem afetar a biomecânica da marcha, mas esse efeito pode ser sobreposto por consequências de doença crítica e tempo em unidade de terapia intensiva. Objetivo Relatar as alterações biomecânicas durante a evolução clínica de um paciente pós-COVID-19 que apresentou comprometimento motor severo após terapia intensiva. Métodos Os dados foram coletados a partir do prontuário do paciente na Fundação José Silveira e dos relatórios médicos anteriores referentes ao período de inter-nação. O paciente estava em cadeira de rodas, com fisioterapia duas vezes por semana, e ao final de 1 ano de acompanhamento era capaz de deambular de forma independente. A análise tridimensional da marcha com cinética e eletromiografia foi realizada em três momentos. Resultados Todos os parâmetros espaço-temporais da marcha, dados cinemáticos, cinéticos e eletromiográficos estavam significativamente alterados quando comparados com a faixa normal de valores. Com a fisioterapia, os indicadores de qualidade da marcha apresentaram melhorias importantes e todos os músculos apresentaram um aumento significativo na magnitude do sinal eletromiográfico (aumento de pelo menos duas vezes). As alterações cinemáticas do tronco diminuíram significativamente neste período. As alterações cinéticas e cinemáticas percebidas nos quadris, joelhos e tornozelos mostraram aproximação do padrão esperado, porém ainda sem normalização, e a coordenação muscular do paciente melhorou com o passar do tempo. Conclusão Este relato é de grande importância clínica, pois descreve, por meio de um laboratório de marcha instrumentado, a evolução de um paciente com comprometimento motor severo após terapia intensiva por COVID-19, quadro pouco descrito na literatura, o que ajudará profissionais de saúde no planejamento de estratégias de reabilitação.

Orthodontic aligners: between passion and science

ABSTRACT Introduction: The benefits and safety of using orthodontic aligners have been reported more by clinical experience and expert opinion than by scientific evidence. Another important aspect is that aligners are constantly evolving. It is important to obtain evidence that allows for new updates in manufacturing technology, in the development of new movement planning protocols, in the incorporation and design of attachments, and in the aid of skeletal anchorage. Methods: Evidence retrieved from six electronic databases (CINAHL, MEDLINE, EMBASE, Psych Info, the Cochrane Library and the Joanna Briggs Library) is presented by means of questions and answers. Conclusions: There is evidence that the aligners presented different levels of difficulty in performing each type of movement, with rotational and vertical movements being the most difficult to perform. Regarding perception of pain due to tooth movement, it seems to have less impact at the beginning of treatment; but dealing with more phonoarticulatory changes seems to require more treatment time in more complex cases. Aligners do not prevent the occurrence of root resorption, although the incidence and severity of resorption may be reduced, making oral hygiene easier and accepting the risk of white spots, caries and periodontal disease. Given the conflicting evidence, the release of bisphenol-A from the aligner cannot be denied. Solutions must be found to reduce the environmental impact of aligners disposal. There is an urgent need for well-designed randomized controlled trials.

RESUMO Introdução: As vantagens e desvantagens do uso de alinhadores ortodônticos têm sido reportadas com base mais na experiência clínica e opinião de experts do que em evidências científicas. Outro aspecto importante é que os alinhadores estão em processo de evolução constante. Assim, torna-se importante obter evidências recentes, que abranjam as novas atualizações na tecnologia de confecção, no desenvolvimento de novos protocolos de planejamento para as movimentações, a incorporação e desenho dos attachments e o auxílio da ancoragem esquelética. Métodos: As evidências encontradas em seis bases de dados eletrônicas (CINAHL, MEDLINE, EMBASE, Psych Info, Biblioteca Cochrane e Biblioteca Joanna Briggs) serão apresentadas por meio de perguntas e respostas. Conclusões: Há evidências de que os alinhadores apresentam diferentes níveis de dificuldade para realizar cada tipo de movimento, sendo os movimentos rotacionais e verticais os mais difíceis de serem executados. Quanto à percepção da dor causada pela movimentação dentária, parece haver menos impacto no início do tratamento, mas os alinhadores produzem mais alterações fonoarticulatórias e parecem exigir mais tempo de tratamento em casos mais complexos. Não há evidência de diferença na estabilidade pós-tratamento, e os alinhadores não impedem a ocorrência de reabsorção radicular, apesar da incidência e a gravidade da reabsorção poderem ser menores, facilitam a higiene bucal, reduzindo o risco de manchas brancas, cáries e doenças periodontais. Dada a evidência conflitante, a liberação de bisfenol-A pelo alinhador não pode ser negada. É preciso encontrar soluções que reduzam o impacto ambiental do descarte dos alinhadores. Há uma necessidade urgente de ensaios clínicos randomizados bem desenhados.

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.

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

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

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

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

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

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

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

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

Observation on the efficacy of traditional Qigong exercise combined with Tuina manipulations in treating lower cervical disc herniation / 针灸推拿医学（英文版）

Objective:To observe the efficacy of traditional Qigong exercise combined with Tuina(Chinese therapeutic massage)manipulations in treating lower cervical disc herniation(CDH).Methods:A total of 120 CDH patients who met the inclusion criteria were randomly divided into an observation group and a control group,with 60 cases in each group.Patients in both groups were given the same Tuina manipulations.In addition,patients in the observation group practiced traditional Qigong exercise,and those in the control group did conventional neck exercise.After 8 weeks of treatment,the efficacy of the two groups was observed.Follow-up was conducted 3 months after the end of the treatment to record any recurrence.Results:The total effective rate of the observation group was higher than that of the control group(P＜0.05).The improvement in symptom scores was more significant in the observation group than in the control group(P＜0.05).There was inter-group statistical significance in comparing the cross-sectional area and fatty infiltration of certain cervical muscles(P＜0.05).In addition,the recurrence rate in the observation group was lower than that in the control group(P＜0.05).Conclusion:On the basis of the same Tuina manipulation treatment,the efficacy of traditional Qigong exercise in treating CDH is superior to that of conventional neck exercise,with more significant improvements in pain and quality of life and a lower recurrence rate.

Biomechanical comparison of spatial weaving and conventional calcaneal plate fixation for calcaneal fracture / 中华骨科杂志

Objective:To compare the biomechanical characteristics of screw only spatial weaving fixation and calcaneal plate fixation in calcaneal fractures.Methods:Sanders type III calcaneus fracture model was established by using calcaneus model specimens: the physiological model group were the normal calcaneal models; the steel plate group were conventional steel plate fixation fracture models; the metal screw group were fracture models with only metal screw weaving fixation; seven and nine absorbable screw spatial weaving groups (seven absorbable screw group, nine absorbable screw group) were used to weave and fix fracture models with seven and nine absorbable screws. Cyclic test and mechanical compression test were carried out, and load-displacement curves were recorded. The material properties of metal screw spatial weaving and calcaneal anatomical plate system were replicated, finite element fracture models were established, and the calcaneal internal fixation models of plate screw group and spatial weaving screw group were completed by reverse processing. The changes of biomechanical characteristics of calcaneal bone in human (70 kg) standing on one foot were simulated, and the distribution of structural strength was analyzed by Von Mises equivalent stress cloud diagram and displacement cloud diagram.Results:In the cyclic test of 20-200 N load, the physiological model group, the plate group, the metal screw group, the absorbable 7 screw group, the absorbable 9 screw group were 0.87±0.22, 0.82±0.08, 0.70±0.12, 1.04±0.13 and 0.83±1.76 mm, the difference in model gap was statistically significant ( F=3.16, P=0.037). Among them, the absorbable 7 screws group was larger than the metal screws group ( t=4.28, P=0.003), and the other pin-two comparisons were not statistically significant ( P>0.05). The deformation of the five groups was 0.37±0.06, 0.38±0.07, 0.38±0.06, 0.52±0.07 and 0.42±0.07 mm, and the difference was statistically significant ( F=4.39, P=0.010). The deformation of absorbable 7 screws group was greater than that of physiological model group, the plate group and metal screw group ( t=3.69, P=0.006; t=3.25, P=0.012; t=3.51, P=0.008). In static test, compression displacement was 7.14±0.79, 7.30±0.66, 6.95±0.28, 8.19±0.61 and 7.16±0.55 mm, the difference was statistically significant ( F=3.28, P=0.032). The displacement of the absorbable 7 screws group was greater than that of the metal screws group ( t=4.13, P=0.003). The stiffness changes were 570.60±122.62, 512.86±80.77, 497.40±66.50, 456.21±58.19 and 560.39±94.40 N/mm, respectively, with no statistical significance ( F=1.44, P=0.258). The results of finite element analysis showed that under 3 500 N axial pressure load, the maximum compression displacement and stiffness of the plate and screw set were 6.47 mm, 540.96 N/mm, and the Von Mises equivalent stress peaks were 450.31 and 353.15 MPa, respectively. The maximum compression displacement and stiffness of the braided screw group were 5.25 mm, 666.67 N/mm, and the peak Von Mises equivalent stress of the screw was 396.20 MPa. Conclusion:Compared with lateral plate fixation, spatial weaving fixation can provide sufficient biomechanical stability for calcaneal healing and is superior to plate fixation in terms of structural stability, which may help to improve the effectiveness of calcaneal fracture fixation.

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

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

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.