Compósito de polihidroxiabutirato (PHB) e hidroxiapatita (HAP-91) como implante ortopédico em gatos (Felis catus)

Abstract

The aim of this study was to evaluate the composite of polyhydroxybutyrate (PHB) 70% and hydroxyapatite (HA) 30% as plates for bone fixation in cats. The employed composite plates presented six orifices and measured 60 and 10 mm, length and width respectively, with thickness ranging from 3 to 5 mm. The plates were subjected to bending, compression and torsion tests, using as reference a 2 mm stainless steel plate. The results were similar for the maximum forces and torque. For the in vivo evaluation, samples of composite were implanted in the subcutaneous tissue and in the femur. Twelve adult mixed-breed cats were used. The cats were randomly distributed into three groups; GI, GII, and GIII, according to the time of evaluation. The assessments were performed at days 15, 30, and 45 for the subcutaneous tissue and at days 30, 60, and 90 for the osseous one. The reaction to the subcutaneous composite was characterized by a granulomatous inflammatory response. In bone, there was formation of a layer of fibrous connective tissue around the composite with predominance of macrophages and giant cells. The composite plate was used in the fixation of femoral osteotomy in four cats, in a total of six interventions. There were ruptures in five plates (83.33%) until Day 4 and in one plate (16.67%) on the Day 21. The results of tissue evaluation demonstrated that the composite does not allow vascular invasion and that it is not osteoconductive. The mechanical tests revealed the minimal ductility of the composite and the clinical results evidenced that the composite does not have sufficient strength to be used as plate of femoral fixation in cats