ABSTRACT
La masificación de la radiología digital ha hecho posible el estudio de diferentes patologías mediante imágenes de alta calidad diagnóstica. Existen diferentes patologías que afectan al tejido óseo, y que producen pérdida del mineral(1). Aquellas patologías se caracterizan por la pérdida de la arquitectura trabecular y un adelgazamiento de la cortical(7), visibles en la radiología. Aquellos cambios llevan al paciente a caer en el riesgo de sufrir futuras fracturas(8), por lo que se considera importante realizar un análisis de la geometría de las trabéculas ante este tipo de patología, con el fin de prever riesgos de fractura. Material y Métodos. Para realizar este estudio, se escogió un fémur de bovino(19). Este fue sumergido en ácido acético al 4 por ciento, con el fin de producir su desmineralización. Se le realizó una medición cada 24 horas mediante la adquisición de imágenes radiológicas, que fueron obtenidas con un equipo digital directo hasta observar cambios radiológicos evidentes en la población trabecular. Las imágenes fueron evaluadas mediante un software de libre acceso llamado ImageJ®(23), realizando mediciones trabeculares mediante la herramienta ROI, y se adquirieron los valores de área, perímetro y circularidad. Resultados. En las 10 trabéculas estudiadas se observaron y cuantificaron cambios en la arquitectura trabecular, aumentando el área en un 124 por ciento, el perímetro en un 53 por ciento y la circularidad se mantuvo en promedio constante. Conclusiones: Mediante la radiología digital, es posible evaluar la arquitectura trabecular mediante parámetros geométricos, los cuales nos indican que existen cambios muy pequeños a lo largo del tiempo. Se observó un aumento de tamaño en las trabéculas, pero sin pérdida de su forma.
Introduction. The mass use of digital radiology has made possible the study of different pathologies through high quality diagnostic images. There are different diseases that affect bone tissue and which produce mineral loss (1). Those diseases are characterized by loss of trabecular architecture and cortical thinning (7), visible in radiology. Those changes lead the patient to suffer the risk of future fractures (8), therefore it is considered important to analyze the geometry of the trabeculae in this kind of pathology in order to anticipate fracture risk. Material and Methods. For this study, a bovine's femur was chosen(19). This was immersed in 4 percent acetic acid to produce demineralization. Measurement was performed (in Clinica Alemana Santiago) every 24 hours by radiological imagings, which were obtained with digital radiology (DR) to observe obvious radiological changes in trabecular population. The images were evaluated by a freely available software called ImageJ® (23), by performing Trabecular measurements using the ROI tool, acquiring the values of area, perimeter and circularity. Results. In the 10 trabeculae studied, we observed and quantified changes in trabecular architecture, increasing the value of average area in 124 percent, perimeter in 53 percent and no change in circularity during the demineralization process. Conclusions. With digital radiography, it is possible to evaluate the trabecular architecture using geometric parameters, which indicate that there are very small changes over time. An increase in size of the trabeculae was observed, trabeculae was observed, but without loss of shape.
Subject(s)
Animals , Bone Demineralization, Pathologic/chemically induced , Femur/pathology , Femur , Radiographic Image Enhancement/methods , Radiographic Image Interpretation, Computer-Assisted , Decalcification, Pathologic/chemically induced , Time Factors , Bone Demineralization Technique/methods , Acetic AcidABSTRACT
PURPOSE: To investigate the postoperative changes and the mechanism of retinal reattachment, the geometric changes of the eye with an encircling scleral buckle was analyzed using a simplified eye model. METHODS: The simplified eye model is an inelastic sphere with an external diameter of 25 mm and an internal diameter of 23.6 millimeters. With an encircling scleral buckle, it was assumed that the circumference of the eyeball would decrease, and in particular with tightening of the buckle, the cross-section of eyeball would be deformed to an ellipsoid shape. The changes in radius, internal surface area, and volume of the eyeball in relationship to the changes in height and span of the silicone buckle were estimated. RESULTS: The radius of eyeball decreased by 0.19-0.90 mm with an encircling scleral buckle, and varied according to the increment of the tightening of the encircling band. The axial length of the eye increased and the volume of the eye decreased also with increased tightening of the band. The scleral arc of the buckle was shorter than the retinal arc of the buckle by 0.09-0.55 mm and the scleral surface area of the buckle was smaller than the retinal area of the buckle by 56-219 mm 2 ; therefore the retina would be redundant. CONCLUSIONS: An encircling scleral buckle changes the axial length and decreases the volume and internal surface area of the eye, making the retina redundant. This redundancy helps resolve or alleviate the problem of a foreshortened retina in retinal reattachment procedures.
Subject(s)
Radius , Retina , Retinal Detachment , Retinaldehyde , Scleral Buckling , SiliconesABSTRACT
Oblique single-plane trochanteric osteotomy, in which an oblique cut is made through the femoral trochanteric area and the bony fragments are rotated at the face of the cut in direct contact with each other, allows simulatenous correction of the femoral neck-shaft angle, femoral anteversion as well as flexion/extension effect. Only approximate methods of calculating the correction effects of this procedure have been introduced. Considering unique spatial orientation of femoral neck, we developed a rigorous method to calculate preoperatively the obliquity of the single-plane osteotomy and the amount of rotation required to achieve the target femoral conformation, through geometric analysis. The correction effect by oblique trochanteric osteotomy on the geometry of proximal femur was dependent not only on the amount of change of the neck-shaft angle and femoral anteversion but also on the preoperative neck-shaft angle and femoral anteversion themselves. The flexion/extesion effect was determined by the direction of the correction and the preoperative neck orientation. Computer graphic simulation study confirmed the validity of this method. A program written in QBASIC was introduced to make this complex calculation method more useful in the clinical practice.