Estudo ex vivo e in vivo de polímero biocompatível comomaterial alternativo na confecção de haste bloqueada pararedução de fraturas em úmero de bezerros

Para o experimento ex vivo, fora utilizados seis pares de úmeros, onde o lado direito foi instrumentado com a haste de polipropileno e bloqueada com quatro parafusos. Em seguida, foram submetidos a testes físicos de flexão e compressão. Os ossos submetidos atécnica foram capazes de resistir a 36,5% da carga suportada pelos ossos íntegros nos testes de flexão e a 66,4% nos testes de compressão. No experimento in vivo, a haste foi implantada em cinco animais que tiveram fratura induzida em seus úmeros. Dos cinco animais, um veio a óbito com oito meses após a cirurgia e o outro com onze dias de pós-cirúrgico. Todos os animais apresentaramdeslizamento dos fragmentos e um apresentou quebra de dois parafusos. A haste foi eficiente em promover estabilidade do foco de fratura, permitindo a consolidação da mesma em todos os casosWith aim to develop an interlocking nail system using polypropilene for long bonefractures repair and to contribute for the treatment of fractures of humerus in bovineneonatos, two experiments were accomplished. In the ex vivo study, six pairs of humeruseswere used. The right ones were fixed with nails interlocked with four screws and the leftones were maintained intact. Physical tests in an universal machine showed that the bonessubmitted to the technique were capable to resist on the average at 36,5% in bending and at66,4% in compression of the load supported by the intact bones. In the in vivo study theinterlocking nail system was implanted in five animals that had fracture induced in itshumeruses. All of them recovered satisfactorily of the anesthesia and could use the memberimmediately after the surgery. In one of the animals the nail broke and had to be substitutedthe following day to the surgery. In spite of the fact that the stability of the fracture hadbeen recovered, this animal had precocious death related to blood parasites. In the otherones, in spite of light misalignment of the fragments in the immediate post-surgery, and theoccurrence of screw break in one of them, bony consolidation was completed at the end ofa 60-days period. Polypropilene presented limited resistance for use as an interlocking nail.However, the system of interlocking nail made of polymer was efficient in promoting bonyrepair in the humerus of neonate calves and it should be a viable alternative for use inclinical cases