Charles Leonardo Israel

Avaliação biomecânica de diferentes métodos de fixação tibial na reconstrução do ligamento anterolateral em ossos suínos

Objective  The present study aims to evaluate different methods of tibial fixation in the reconstruction of the anterolateral ligament (ALL). In addition, the present paper aims to compare the effectiveness of these methods and their mechanisms of failure in swine knees. Methods  A total of 40 freshly frozen swine limbs were divided into 4 groups of 10 specimens, according to the tibial fixation technique used. In group A, the tibial fixation of the tendon graft was made through an anchor passing the graft. In group B, the tibial fixation was performed through a metal interference screw in a single bone tunnel. In group C, the tibial fixation included an anchor associated with a tendinous suture (but not with a wire crossing the tendon). In group D, two confluent bony tunnels were drilled and combined with an interference screw in one of them. Results  The lowest mean force (70.56 N) was observed in group A, and the highest mean force (244.85 N) was observed in group B; the mean values in the other 2 groups ranged from 171.68 N (group C) to 149.43 N (group D). Considering the margin of error (5%), there was a significant difference between the groups ( p  < 0.001). Conclusion  Fixation with an interference screw in a single tunnel bone showed the highest tensile strength among the evaluated techniques.

Comparative study of quenched and austempered ductile cast irons

This work aims to evaluate the mechanical properties of three different materials, relating the tests results with the metallurgical features of the samples. The first and the second material were an austempered ductile cast iron (austempering temperatures of 260 and 3000C, respectively). The third material was a quenched and tempered ductile cast iron. Impact, tension and hardness tests were employed in the mechanical characterization of the materials. In the metallurgical characterization, optical microscopy and image analysis were employed. It was observed that in the impact tests, the austempered ductile iron in the temperature range of 3000C was the material with higher toughness. In this material, low hardness allied to the high retained austenite level (21%), were the main factors acting in the higher impact resistance of the 3000C austempered cast iron. Key words: ADI, mechanical properties, retained austenite.