Ensaio biomecânico para determinação do diâmetro de barra conectora de polimetilmetacrilato em fixador esquelético externo tipo Ia: no úmero de suínos

Abstract

While seemingly inert appearance, bones are highly dynamic structures, which promote formation, resorption, repair and maintenance of homeostasis. Fractures in bones occur when the load applied to a specific bone region exceeds its resilience. The use of external skeletal fixator (ESF) is a method of fairly common internal stabilization, in which connector bars polymethylmethacrylate (PMMA) are used without criterion in diameter. In these cases, it can break if it gets too thin or too heavy and uncomfortable when bulky. The aim of this study was to test biomechanical through axial compression and bending, considering different connector bar diameter PMMA correlated to bone diameter for use to type Ia ESF. For this, it was collected 24 swine humerus to make measurements of length, diameter, circumference and testing biomechanical. After the bars confected with 1.5 times the average diameter of the bone (group I), the same diameter bone (group II) and 0.5 times the diameter of the bone (group III). The results obtained, it was observed that the connector bars in group II were more resistant than the bones in the compression test. In the bending test, the bones resisted flexion strength when compared to group III. The group II was 4.3 times more resistant than Group III in the same mechanical test. The results allow a direction for making bars PMMA considering bone diameter as a reference.