Jésica Andrea Isaza

Analysis of bone demineralization due to the use of exoprosthesis by comparing Young’s Modulus of the femur in unilateral transfemoral amputees

Background: There is a relation between Hounsfield units obtained from computed tomography (CT) scans and bone density. The density of the bones can be used to establish its mechanical properties and therefore to assess the bone mechanical condition using CT images. Objectives: To identify the effect of the transfemoral amputation and the use of external lower limb prosthesis in the bone properties, by comparing Young’s modulus. Study Design: Young’s modulus comparison. Methods: Comparison of bone density between the healthy femur and the amputated bone of 20 unilateral transfemoral amputees was done by generating three histograms of the Hounsfield units at different parts of the femur. The histograms were created based on images obtained by CT and the Hounsfield units were translated to Young’s modulus to establish the comparison. Results: The results show a significant difference (p-value <0.05) between the mean value of Young’s modulus of healthy and amputated bone. Conclusions: There is clearly a direct association between the use of external prosthesis and the bone demineralization due the stress shielding phenomenon. The Young’s modulus comparison using information from CT images can be a suitable tool to analyze the bone demineralization due to the use of exoprosthesis.

Pores distribution statistical analysis for metal foams obtained by casting-dissolution process

Interesting properties of metal foams such as light weight, good energy absorption and low thermal conductivity, have promoted the development of new processes to improve properties without sacrificing productivity. This study aims to verify the uniformity pore distribution in an aluminum alloy foam obtained by Casting - Dissolution Process, using a nondestructive analysis. In order to evaluate mechanical properties of a metal foam using computational numerical models, the use of a small reconstructed section of the sample representing an entire volume of metal foam, was validated. In conclusion, it was possible to determine that all parts of the sample have the equivalent superficial area and volume.