Three-dimensional dynamic analysis of the effect of pelvic rotation around coronal axis on acetabular prosthesis / 中华骨科杂志

Objective:To investigate the effect of pelvic rotation around coronal axis on the placement angle of acetabular prosthesis after total hip arthroplasty.Methods:According to Murary's definition, the angle between the acetabular axis and the sagittal plane was defined as the acetabular abduction angle, and the angle between the acetabular axis and the coronal plane as the anterior inclination angle. A simple mathematical solid geometry model was established by using the mathematical software GeoGebra to simulate the dynamic changes of the acetabular prosthesis when it rotated around the coronal axis, and the calculation formula of the dynamic changes of the anterior inclination and abduction angle of the acetabular prosthesis was derived. MatLab software was used to generate the function graph of pelvis forward inclination and abduction angle and deduce the motion of acetabular prosthesis.Results:The dynamic changes of acetabular tilt angle and abduction angle when the pelvis rotated around the coronal axis were functionally related to the anterior-posterior tilt of the pelvis in a nonlinear pattern. When the pelvis rotates around the coronary axis, the anterior inclination angle formula is α 1=arcsin (sinβ 1×cosα×cosθ+cosβ 1×sinα); When the acetabulum axis faces downwards the abduction angle formula is θ 1=arccot (cosβ 1×cotθ-sinβ 1×tanα/sinθ); When the acetabulum axis faces upwards the abduction angle formula is θ 1=π-abs[arccot (cosβ 1×cotθ-sinβ 1×tanα/sinθ)] withα being the initial acetabular forward angle, θ being the initial acetabular abduction angle, α 1 being the forward angle of the acetabular prosthesis after pelvic rotation, θ 1 being the external expansion angle of the acetabular prosthesis after pelvic rotation and β 1 being the rotation angle of the pelvis around the coronal axis. When the pelvis is tilted backward, the anterior inclination angle of the acetabular prosthesis increases first and then decreases, and the abduction angle continues to increase. When the pelvis is tilted forward, the abduction angle decreases first and then increases, and the anterior inclination angle continues to decrease to negative. Conclusion:When the initial anterior inclination angle and abduction angle of acetabular prosthesis change, the curve of anterior inclination and abduction angle change accordingly. The larger the initial anterior inclination angle is, the faster it reaches its peak value, and the larger the peak value is, the faster the abduction angle changes. The larger the initial abduction angle is, the slower the initial anterior inclination angle and the abduction angle change.

Análise isocinética e cinética de corredores e triatletas com e sem histórico de fratura por estresse / Isokinetic and kinetic analysis in runners and triathletes with and without history of stress fracture / Análisis isocinético y cinético en corredores y triatletas con y sin historial de fracturas de estrés

INTRODUÇÃO: A associação da fadiga muscular com o aumento da força vertical de reação do solo representa risco de fratura por estresse de tíbia em esportes como a corrida de longa distância e o triatlo. Objetivo: Analisar e comparar parâmetros do componente vertical das forças de reação do solo e parâmetros musculares isocinéticos da flexão plantar (FP) e dorsiflexão (DF) do tornozelo entre grupos de corredores de longa distância e triatletas com e sem histórico de fratura por estresse de tíbia.MÉTODOS: Setenta e cinco atletas de corrida de longa distância e triatletas do sexo masculino, com média de idade de 30,26 ± 6,51 anos foram divididos de acordo com a história pregressa de fratura por estresse de tíbia em: grupo fratura (GF), composto por 12 indivíduos com história de fratura por estresse da tíbia, e grupo não-fratura (GNF), composto por 37 indivíduos sem história de fratura por estresse de tíbia. Os parâmetros cinéticos foram medidos durante a corrida por meio de uma plataforma de força AMTI, e os parâmetros isocinéticos por meio de dinamômetro isocinético Biodex (System 3).RESULTADOS: Para todas as variáveis isocinéticas e cinéticas, não houve diferenças entre GF e GNF.CONCLUSÃO: Ainda que não se tenha identificado uma diferença de desempenho entre os grupos estudados, o perfil cinético (impacto) e isocinético (atividade muscular) mostra que o treinamento da corrida com déficits em cuidados com a condição muscular e o controle de fatores extrínsecos pode criar uma situação de risco de ocorrência de fraturas por estresse.

INTRODUCTION: The association of muscle fatigue to increased vertical ground reaction force imposes the risk of tibial stress fracture in sports like long-distance running and triathlon. Objective: To analyze and compare parameters of the vertical component of ground reaction forces and isokinetic muscle parameters of plantar flexion (PF) and dorsiflexion (DF) of the ankle between groups of distance runners and triathletes with and without a history of tibial stress fracture.METHODS: Seventy-five male long-distance runners and triathletes with a mean age of 30.26±6.51 years were divided according to the previous history of tibial stress fracture: fracture group (FG), composed 12 individuals with a history of stress fracture of the tibia and non-fracture group (NFG), composed of 37 individuals with no history of stress fracture of the tibia. The kinetic parameters were measured during the run through a force platform AMTI and isokinetic parameters through an isokinetic dynamometer Biodex (System 3).RESULTS: For all isokinetic variables and kinetics, there were no differences between FG and NFG.CONCLUSION: Although a difference in performance has not been identified between groups, the kinetic profile (impact) and isokinetic impact (muscle activity) shows that the running training with deficits in muscle condition care and control of extrinsic factors can create a risk of occurrence of stress fractures.

INTRODUCCIÓN: La asociación de la fatiga muscular al aumento de la fuerza vertical de reacción del suelo representa un riesgo de fractura por estrés de la tibia en deportes como las carreras de fondo y triatlón. Objetivo: Analizar y comparar los parámetros del componente vertical de las fuerzas de reacción del suelo y los parámetros musculares isocinéticos de flexión plantar (FP) y dorsiflexión (DF) del tobillo entre grupos de corredores de fondo y triatletas con y sin antecedentes de fractura por estrés de la tibia.MÉTODOS: Setenta y cinco atletas de carreras de larga distancia y triatletas del sexo masculino, con un promedio de edad de 30,26 ± 6,51 años fueron divididos de acuerdo con el historial clínico anterior de fractura por estrés de tibia, en: grupo fractura (GF) compuesto por 12 individuos con antecedentes de fractura por estrés de la tibia, y grupo no-fractura (GNF), compuesto por 37 individuos sin antecedentes de fractura por estrés de la tibia. Se midieron los parámetros cinéticos durante la carrera por medio de una plataforma de fuerza AMTI y los parámetros isocinéticos a través de un dinamómetro isocinético Biodex (System 3).RESULTADOS: Para todas las variables isocinéticas y cinéticas, no hubo diferencias entre GF y GNF.CONCLUSIÓN: A pesar de que no se haya identificado una diferencia de rendimiento entre los grupos estudiados, el perfil cinético (impacto) e isocinético (actividad muscular) demuestra que el entrenamiento de carrera con déficit en el cuidado de la condición muscular y control de los factores extrínsecos puede crear un riesgo de aparición de fracturas por estrés.

Quantitative analysis of segmental left ventricular wall motion using a polar representation of color kinesis images / Avaliação quantitativa da mobilidade segmentar do ventrículo esquerdo utilizando uma representação polar das imagens de "color kinesis"

A "color kinesis (CK) é uma técnica que representa o tempo e a magnitude da mobilidade global e segmentar do ventrículo esquerdo (MSVE) em tempo real. Neste estudo descreve-se um novo método para representar estas imagens na forma "bulls-eye" em mapas polares que provêem uma avaliação integrada e objetiva da MSVE. Foram avaliados indivíduos normais e em pacientes apresentando anormalidades na MSVE no estudo ecocardiográfico bidimensional com o objetivo de verificar a capacidade desta técnica para identificar e quantificar automaticamente a disfunção ventricular. Os dados obtidos demonstram que, embora a representação polar de imagens de CK seja factível em uma elevada proporção de indivíduos e possa proporcionar uma avaliação quantitativa da MSVE mais objetiva e menos dependente do operador, essa ferramenta de processamento de imagens mostrou limitada capacidade para identificação automática de disfunção ventricular quando comparada com a análise de observadores experientes.

The kinematic analysis of different prosthesis after the total knee arthroplasty / 中华骨科杂志

Objective To explore the effect of the antero-posterior translation of the femur on the maximum knee flexion and the relative movement of the femur for the three different kinds of prosthesis after total knee arthroplasty(TKA), such as posterior-stabilizing, fixed-bearing and mobile-bearing with the PCL retention. Methods 25 patients were selected for each kind of the prosthesis, and the inclusion criterion was based as the knee OA, good-excellent outcome after TKA, the flexion of the knee beyond 90?, and more than one year follow-up. The average age of these patients was 68 years with a range of 63 to 77 years, which involved 32 males and 43 females. The average preoperative knee flexion in the three groups were 77.8??15.1?, 80.1??12.9? and 76.4??12.7? respectively. The roentgenograms were taken both at the knee extension and maximum flexion, then the femur translation and the knee flexion were measured. Results The difference of the knee flexion among three groups preoperatively was of no significance. The maximum postoperative knee flexion in the posterior stabilizing, fixed-bearing and mobile-bearing was 118.0??7.1?,108.7??7.9? and 100.2??8.3? respectively. The analysis of variance showed the difference was of significance (F=32.86, P=0.0001). The relative movement about the femoral prosthesis in the three groups were (6.3?2.5) mm, (1.2?4.6) mm and ( 4.7?3.7) mm respectively (the posterior movement was positive, and the anterior was negative). The difference was of significance(F=57.71, P=0.0001). The femoral antero-posterior translation was proved to have correlation with the maximum knee flexion. Conclusion The femoral translation among three groups are different in manner, accordingly, the maximum knee flexion was different too.