RESUMO
Resumen En el trabajo se plantea el análisis de diferentes geometrías para un dispositivo intramedular, las cuales ayudan a reducir y evitar la migración, deformación y rotura del implante en tejido óseo afectado con Osteogénesis Imperfecta (OI). Se realizaron diseños en CAD de diferentes prototipos, donde se analizan las propiedades mecánicas en el alma del dispositivo, así como en las roscas distal y proximal de los implantes macho y hembra. Asimismo, se obtuvieron modelos 3D de huesos de un infante afectado con OI para realizar simulaciones mediante elemento finito de la interacción entre el hueso y el dispositivo intramedular. Los resultados muestran que los prototipos propuestos disminuyen la deformación del dispositivo, así como el aumento en la rigidez de la relación hueso-prótesis. Asimismo, las roscas generaron un menor esfuerzo en la unión con el hueso, lo que prevé un menor daño al tejido óseo. El trabajo se limitó al análisis numérico del rediseño de implantes telescópicos intramedulares para afectados con OI. Concluyendo que la geometría semicircular 3/4 de caña, otorga un óptimo resultado en las pruebas realizadas, al tiempo que las roscas ACME proveen una mejor sujeción en las epífisis distal y proximal de los huesos largos.
Abstract In this work we propose the analysis of different geometries for an intramedullary device, which help to reduce and avoid the migration, deformation and rupture of the implant in bone tissue affected with Osteogenesis Imperfecta (OI). Designs of different prototypes were made in CAD, where the mechanical properties in the device's soul are analyzed, as well as in the distal and proximal threads of the male and female implants. Likewise, 3D bone models of an affected infant with OI were obtained to perform finite element simulations of the interaction between the bone and the intramedullary device. The results show that the prototypes proposed decrease the strain of the device, as well as the increase in the stiffnes of the bone-prosthesis relationship. Also, the threads generated less stress in the union with the bone, which provides less damage to the bone tissue. The work was limited to the numerical analysis of the redesign of intramedullary telescopic implants for patients with OI. Concluding that the semicircular geometry 3/4 of cane, gives an optimal result in the tests carried out, while the ACME threads provide a better subjection in the distal and proximal epiphyses of the long bones.
RESUMO
This work studies descriptively the Head Injury Criterion (HIC) and Chest Severity Index (CSI), with a finite element model of the Hybrid III dummy type, for six-year-old subjects in a frontal vehicular collision, using the low-back booster (LBB) passive safety system. The vehicle seats and the passive safety systems were modelled in CAD (computer aided design) software. Then, the elements were analysed by the finite element method (FEM) in LS-DYNA® software. The boundary conditions were established for each study, according to the regulations established by the Federal Motor Vehicle Safety Standard (FMVSS), following the FMVSS 213 standard. The numerical simulations were performed during an interval of 120 ms and recording results every 1 ms. In order to analyse the efficiency of the system, the restraint performance of the LBB system is compared with the restraint configuration of the vehicle safety belt (VSB) only. The obtained injury criteria with the LBB system shows its ability to protect children in a frontal collision. The analyses allow obtaining the deceleration values to which the dummy head and chest was subjected. Of the studies herein performed, Study I: VSB obtained a HIC36 of 730.4 and CSI of 315.5, while Study II: LBB obtained a HIC36 of 554.3 and CSI of 281.9. The outcome shows that the restraint efficiency of each studied case differs. Used materials, the attachment system of the LBB, and the belt restraint system properly placed over the infant trunk are the main factors reducing the injury criteria rate.
