RESUMO
OBJECTIVE: The study aimed to evaluate three different degrees of correction in the surgical treatment of neglected developmental dysplasia of the hip (DDH) using finite element models based on computed tomography. METHOD: Three tridimensional FEA models of hypothetical post-operative (PO) outcomes were developed, based on three tridimensional CT of a pediatric patient diagnosed with luxated neglected DDH: One with the acetabular index of the contralateral hip (CLAT); another based on a theoretical Bombelli biomechanical model (BMB); and another recreating the patient's actual PO. RESULTS: The stresses in the affected hip were greater than those in the unaffected hip. CLAT showed the greatest stress and the smallest loading zone (LZ). In contrast, BMB showed the smallest stress and the biggest LZs. CONCLUSIONS: The approach based on the BMB gave the best results in terms of the distribution of the stresses over the hip, whereas the worst was CLAT. Qualitatively, estimating the stability and range of movement of the hip, the PO case was considered the best.
OBJETIVO: Evaluar tres diferentes grados de corrección en el tratamiento quirúrgico de la displasia del desarrollo de la cadera (DDH) inveterada mediante modelos de elementos finitos basados en tomografía computarizada. MÉTODO: Se desarrollaron tres modelos tridimensionales de elementos finitos de resultados posoperatorios hipotéticos, basados en tres tomografías computarizadas tridimensionales de un paciente pediátrico diagnosticado de displasia del desarrollo de la cadera luxada inveterada: uno con el índice acetabular de la cadera contralateral (CLAT), otro basado en un modelo biomecánico teórico de Bombelli (BMB) y otro recreando el posoperatorio real (PO) del paciente. RESULTADOS: Los esfuerzos en la cadera afectada fueron mayores que en la cadera no afectada. El CLAT mostró el mayor esfuerzo y la menor zona de carga. Por el contrario, el BMB mostró el menor esfuerzo y las mayores zonas de carga. CONCLUSIONES: La propuesta basada en el BMB dio los mejores resultados en cuanto a la distribución de los esfuerzos sobre la cadera, mientras que la peor fue el CLAT. Cualitativamente, estimando la estabilidad y la amplitud de movimiento de la cadera, el caso PO se consideró el mejor.
Assuntos
Displasia do Desenvolvimento do Quadril , Análise de Elementos Finitos , Tomografia Computadorizada por Raios X , Humanos , Displasia do Desenvolvimento do Quadril/cirurgia , Luxação Congênita de Quadril/cirurgia , Fenômenos Biomecânicos , Estresse Mecânico , Acetábulo/cirurgia , FemininoRESUMO
Ankle arthrodesis is the gold standard for treatment of end-stage arthritis. The goal of ankle arthrodesis is to obtain bony union between the tibia and the talus. Retrograde intramedullary nailing is typically reserved for ankle and subtalar joints arthrodesis. The purpose of this study is to evaluate the effect of two different materials, two locking pin configurations and two nail designs of a retrograde locked intramedullary nail used for ankle arthrodesis. Using the finite element analysis, a numerical study of ankle arthrodesis was developed to evaluate the effect of materials: TI-6Al-4V and stainless steel AISI 316 LVM; two locking pin configurations: five and six pins, on two intramedullary nails: Ø10 × 180 mm and Ø11 × 200 mm. A model of a healthy foot was created from tomographic scans. It was found that the mechanical stimulus required to achieve bone fusion were higher for Ø10 × 180 nails (6.868 ± 0.047) than the Ø11 × 200 nails (5.918 ± 0.047; p < 0.001; mean ± SEM). We also found that six-pin configuration had a higher mechanical stimulus (6.470 ± 0.047) than the five-pin configuration (6.316 ± 0.046; p = 0.020). Similarly, it was higher for titanium (6.802 ± 0.047) than those for stainless steel (5.984 ± 0.046; p < 0.001). Finally, the subtalar zone presented higher values (7.132 ± 0.043) than the tibiotalar zone (5.653 ± 0.050; p < 0.001). The highest mechanical stimulus around the vicinity of tibiotalar and subtalar joint was obtained by Ø10 × 180 nails, made of titanium alloy, with 6P.
Assuntos
Tornozelo , Fixação Intramedular de Fraturas , Análise de Elementos Finitos , Aço Inoxidável , Titânio , Pinos Ortopédicos , Articulação do Tornozelo/diagnóstico por imagem , Articulação do Tornozelo/cirurgia , Fixação Intramedular de Fraturas/métodos , ArtrodeseRESUMO
BACKGROUND: The reconstruction of the proximal humerus is possible from the resection of the tumor and the placement of a prosthesis. In some cases, they do not meet the anthropometric aspects of the patients. OBJECTIVE: To determine the parameters to size the components of a humeral prosthesis and the development of a set, using design software. METHOD: Forty patients were selected for prostheses, radiographs and CT scans were analyzed and statistical tests were applied to the measurements. RESULTS: The length of the tumors was 8-20 cm. The minimum length of the humerus was 28 cm and 33 cm the maximum. Correlation was observed between the humerus and the tumor and the height of the patient with p = 0.93088 and p = 0.904564, respectively; humerus diameter, p = 0.2345. The set will include three components, diameter 6-10 mm, and length of 24, 26 and 28 cm. Three modular spacers with lengths of 6, 8.5 and 13 cm. Crowns 6.5 and 8.5 cm long, 1.3 cm in diameter and 5 mm nut. CONCLUSION: With the development of the set, poorly calculated resections and adaptation to any humerus size can be resolved.
ANTECEDENTES: La reconstrucción del húmero proximal es posible a partir de la resección del tumor y la colocación de una prótesis. En algunos casos, las prótesis no cumplen con los aspectos antropométricos de los pacientes. OBJETIVO: Determinar los parámetros para dimensionar los componentes de una prótesis de húmero y el desarrollo de un set, mediante software de diseño. MÉTODO: Se seleccionaron 40 pacientes para prótesis, se analizaron radiografías y tomografías computarizadas, y se aplicaron pruebas estadísticas a las mediciones. RESULTADOS: La longitud de los tumores fue de 8-20 cm. La longitud mínima del húmero fue de 28 cm y la máxima fue de 33 cm. Se observó correlación entre el húmero y el tumor y la altura del paciente, con p = 0.93088 y p = 0.904564, respectivamente; para el diámetro del húmero, p = 0.2345. El set incluye tres componentes, con diámetro de 6-10 mm y longitud de 24, 26 y 28 cm; tres espaciadores modulares con longitudes de 6, 8,5 y 13 cm; coronas de 6,5 y 8,5 cm de largo, 1,3 cm de diámetro y tuerca de 5 mm. CONCLUSIÓN: Con el desarrollo del set se pueden resolver resecciones mal calculadas y la adaptación a cualquier tamaño de húmero.
Assuntos
Neoplasias Ósseas , Osteossarcoma , Neoplasias Ósseas/diagnóstico por imagem , Neoplasias Ósseas/cirurgia , Humanos , Úmero/diagnóstico por imagem , Úmero/cirurgia , Próteses e Implantes , Desenho de Prótese , Resultado do TratamentoRESUMO
INTRODUCTION: Mini-implants are an alternative to traditional methods of anchorage in orthodontic treatment. However, there are still questions concerning their application, in particular, with the insertion angle. OBJECTIVE: To determine whether the angle of insertion of the mini-implant is a determining factor in their primary stability when they support orthodontic loads. MATERIALS AND METHODS: A finite element model (FEM) of tibia bone, spring and mini-implant was developed. The three-dimensional model of the rabbit tibia was constructed based on tomographic slices. The angles that were analyzed were 90°, 80°, 70°, 60°, 50°, 45°, 40°, and 30°. A horizontal force of 2 N applied to the head of the mini-implants was simulated. The von Mises stresses and displacements were determined using FEM. RESULTS: Von Mises stresses were lower for an insertion angle of 40° followed by 90° and 70°; likewise, the displacements of the mini-implants with respect to the spring were lower for the 40° angle followed by 90° and 70°, we found a statistically significant association between the insertion angle and displacement. CONCLUSION: All mini-implants underwent a degree of angulation and displacement; however, mini-implants inserted to the bone surface at 40° tend to have better primary stability, and they can withstand loads immediately.
INTRODUCCIÓN: Los miniimplantes son una alternativa para los métodos de anclaje tradicionales en el tratamiento de ortodoncia. Sin embargo, existen interrogantes referentes a su uso, en particular en cuanto al ángulo de inserción. OBJETIVO: Determinar si el ángulo de inserción es un factor determinante en la estabilidad primaria de los miniimplantes cuando soportan cargas. MÉTODO: Se desarrolló un modelo tridimensional de elementos finitos del conjunto tibia, miniimplante y resorte a partir de cortes tomográficos; finalmente, el resorte fue modelado empleando elementos de contacto. Las angulaciones analizadas fueron 90°, 80°, 70°, 60°, 50°, 45°, 40° y 30°. Una fuerza de 2 N fue aplicada a los implantes. Se determinaron los esfuerzos de von Mises y los desplazamientos empleando elementos finitos. RESULTADOS: Los esfuerzos de von Mises fueron menores para un ángulo de inserción de 40°, seguido por los de 90° y 70°; de igual forma, los desplazamientos en los miniimplantes con respecto al resorte fueron menores para un ángulo de 40°, seguido por los de 90° y 70°. CONCLUSIÓN: Todos los miniimplantes presentaron un cierto grado de angulación y desplazamiento, pero los insertados en la superficie ósea a 40° tienden a presentar mejor estabilidad primaria y pueden ser inmediatamente sometidos a carga.
Assuntos
Análise de Elementos Finitos , Modelos Anatômicos , Procedimentos de Ancoragem Ortodôntica/instrumentação , Procedimentos de Ancoragem Ortodôntica/métodos , Animais , Fenômenos Biomecânicos , Coelhos , Estresse Mecânico , TíbiaRESUMO
Las úlceras por presión son las complicaciones secundarias más comunes a una lesión medular, las cuales ponen en riesgo tanto la salud como la vida de quienes las padecen. Las úlceras por presión más comunes en lesionados medulares aparecen en la región pélvica, principalmente en las tuberosidades isquiáticas (TI's). Una estrategia usada en la clínica es medir la presión generada entre el paciente y la superficie donde se encuentra para evaluar el riesgo que representa dicha superficie para el desarrollo de úlceras por presión sin embargo, este tipo de mediciones superficiales no garantizan que la presión en los tejidos internos subyacentes a prominencias óseas sea inocua. Con el fin de estudiar los mecanismos de formación de úlceras por presión, se realizó el análisis de un modelo de pelvis y tejido subyacente por medio del Método de los Elementos Finitos (MEF). De esta manera se puede estudiar el comportamiento de las TI's sobre su tejido circundante, así como analizar los efectos biomecánicos que provocan las úlceras. Se construyó el modelo computacional por medio de un software de CAD (Computing Aided Design) de la pelvis a partir de cortes tomográficos. El modelo fue exportado al software COMSOL y se analizaron seis casos de estudio: un análisis de la pelvis sobre bloques de tejido sano y cinco casos más, los cuales simulan lesiones en el tejido con distintas profundidades, representando úlceras superficiales e internas. Los resultados mostraron que los puntos de máximo esfuerzo, en todas las pruebas, se localizan justo debajo de la TIs además se encontró que las lesiones internas presentan mayores esfuerzos y deformaciones, los cuales pueden ser precursores de daño en el tejido.
Pressure ulcers are the most common secondary complication to a spinal cord injury, which endanger both health and life of the patients who suffer them. The most common pressure ulcers in spinal cord injuries occur in the pelvic region, mainly in the ischial tuberosities (ITs). A strategy used in clinic is to quantify the pressure generated between the patient and the surface, in order to assess the risk posed by that surface for developing pressure ulcers. Despite this, this type of surface measurements does not guarantee that pressure in the internal tissues underlying to bony prominences, to be safe. In order to study the mechanisms of formation of pressure ulcers, an analysis of a model of the pelvis and its underlying tissue was performed using the Finite Element Method (FEM). By this means we can study the behavior of ITs on its surrounding tissue, and at the same time, we analyze the biomechanical effects those cause ulcers. The computational model of the pelvis was built from tomographic slices using CAD software (Computing Aided Design). The model was exported to the finite element software COMSOL and six study cases were analyzed: an analysis of the pelvis on healthy tissue blocks and five more cases, which simulate tissue injury with different depths, representing surface and internal ulcers. The results showed that the maximum stress points in all tests are located just below the ITs it was also found that internal injuries present higher stresses and strains, which can be precursors of tissue damage.
Assuntos
Humanos , Fenômenos Biomecânicos/fisiologia , Análise de Elementos Finitos , Úlcera por Pressão/fisiopatologia , Imageamento Tridimensional , Ísquio/fisiopatologiaRESUMO
INTRODUCTION: Nonalcoholic fatty liver disease (NAFLD) is characterized by high intrahepatic triglyceride level. It is associated with an increased prevalence of cardiovascular disease, independently of underlying cardiometabolic risk factors. Metformin is used as a pharmacological treatment; the adherence is low because of the presence of adverse effects. Aerobic exercise could be an alternative therapy, but its effectiveness compared with metformin has not been established in the treatment of NAFLD. The aim of this study was to establish the effectiveness of aerobic exercise and its influence in reducing cardiovascular risk in overweight or obese women with NAFLD. MATERIAL AND METHODS: Sedentary women 25-60 years old with body mass index (BMI) > 24.9 kg/m2 and liver fat content < 50 HU, were randomly divided into two parallel groups: exercise group (EG) or metformin group (MG). The EG performed an aerobic exercise program of 60 min/5 days/ week at 60-85% of heart rate reserve; the MG took 1 g/day of metformin each morning. The duration of the intervention was 12 weeks. The liver fat content, metabolic and cardiorespiratory- fitness parameters were evaluated at the beginning and end of the program. The study complied with the Helsinki ethics codes for human research. RESULTS: The study included a sample of 16 women, with 8 per group. The treatments modified the liver fat content by 14.6% (CI95% 0.92, 28.36) and 10.37% (CI95% -1.74, 22.48) for the EG and MG, respectively. In the EG, the insulin levels and HOMA-IR decreased (P < 0.05), and the cardiovascular fitness improved. CONCLUSIONS: An aerobic exercise program of 12 weeks with a volume training of 300 min/week and a moderate to vigorous intensity (60-85% VO2peak) modified the liver fat content and improved cardiovascular risk factors during the intervention. Exercise contributed to a holistic approach by modifying a number of the components of metabolic syndrome, cardiorespiratory-fitness, and cardiovascular risk.
Assuntos
Terapia por Exercício , Fígado Gorduroso/terapia , Metformina/uso terapêutico , Adulto , Exercício Físico , Fígado Gorduroso/complicações , Fígado Gorduroso/tratamento farmacológico , Feminino , Humanos , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica , Obesidade/complicações , Sobrepeso/complicaçõesRESUMO
Cervical spine dysmorphisms (CSD) occurs in an heterogeneous group of patients unified by the presence of congenital defects result from malalignment, formation or segmentation of the cervical spine; generating disability. This problem requires comprehensive evaluation of patients with scoliosis diagnosis, correlating clinical and radiological findings and the presence of numerous abnormalities of other systems in order to give an opportunely syndrome diagnosis and multidisciplinary management of this patients with the aim to give them an integral rehabilitation treatment increasing their quality of life. In this study we described clinical and radiological findings in children with CSD diagnosis. We studied 47 consecutive outpatients of Pediatric Rehabilitation Division in Instituto Nacional de Rehabilitaci6n (INR) with scoliosis diagnosis. Sixteen patients (34%) had CSD diagnosis. Most frequently syndromes (Sx) were: Klippel-Feil Sx (19%), Wildervanck (4.3%), neurofibromatosis (4.3%), Morquio (2.1%), Stickler (2.1%) and Williams (2.1%). We found CSD diagnosis in 34% of group studied, greater than medical literature.