Surgical planning and patient-specific biomechanical simulation for tracheal endoprostheses interventions.

We have developed a system for computer-assisted surgical planning of tracheal surgeries. The system allows to plan the intervention based on CT images of the patient, and includes a virtual database of commercially available prostheses. Automatic segmentation of the trachea and apparent pathological structures is obtained using a modified region growing algorithm. A method for automatic adaptation of a finite element mesh allows to build a patient-specific biomechanical model for simulation of the expected performance of the implant under physiological movement (swallowing, sneezing). Laboratory experiments were performed to characterise the tissues present in the trachea, and movement models were obtained from fluoroscopic images of a patient. Results are reported on the planning and biomechanical simulation of two patients that underwent surgery at our hospital.

ANÁLISIS BIOMECÁNICO DE LA EPIFISIOLISIS DE LA CABEZA FEMORAL: COMPARACIÓN ENTRE FÉMURES SANOS Y ENFERMOS

En este trabajo se desarrolla un análisis por elementos finitos cuyo objetivo principal es determinar las diferencias de tensiones en la placa de crecimiento que se producen entre fémures sanos, con epifisiolisis unilateral y con epifisiolisis bilateral, para evaluar sus posibles causas. Se elaboraron los modelos de elementos finitos correspondientes a 45 pacientes. Los resultados mostraron un patrón de esfuerzos similar en todos los grupos de fémures y, además, la aparición de tensiones mayores en el grupo con epifisiolisis con respecto al grupo control. Se observó también que el valor del ángulo axial-fisis dependía significativamente del tipo de fémur analizado, y, además, una mayor influencia de los factores geométricos en la incidencia de la enfermedad, en comparación con la del índice de masa corporal.

In this work, a finite element analysis (FEA) is accomplished to study the differences of stresses in the growth plate, that are produced in healthy and unhealthy femurs, and to evaluate the possible causes of this illness. Finite element models of 45 patients were developed. The results demonstrated a similar pattern of stresses in all the groups of femurs and also the appearance of greater stresses in the group with slipped capital femoral epiphysis than in the control group. It was also observed a strong dependency on the value of the axial-fisis angle from the group of femur analyzed and a bigger influence of the geometric factors than of the body mass index, in the incidence of the illness.