Compósito de hidroxiapatita e lignina como promotor de osseointegração entre implante metálico e tecido ósseo: estudo experimental

• Autor(a) principal: Martinez, Mastoby Miguel Martinez
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4942
• topic: Reparação óssea; Hidroxiapatita; Resistência mecânica; Bone regeneration; Hydroxyapatite; Mechanical resistance; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::CLINICA E CIRURGIA ANIMAL::CLINICA CIRURGICA ANIMAL

This study aimed to evaluate the composite made of synthetic hydroxyapatite associated with lignin, as a promoter of integration between a metal implant (intra-medullar pin, Schanz) and bone tissue. Twenty New Zealand rabbits were used, each of them had both tibia operated: the left one was treated with the composite and the right was not treated, serving as control. A 4mm diameter defect was made in the lateral side of the proximal tibia, reaching the medullar canal. Ten drops of saline solution were added to 1000mg of the composite, resulting in a mass, part of it was used to cover the thread end of the Schanz steel F 138 intra-medullar pin for cortical bone, size 2.5mm. Te other party was inserted in the medullar canal of the treated group with the help of a size 16 catheter and disposable syringe. After the insertion of the 7cm pin in the medullar canal, the cortical defect was filled with 400mg of the composite. The same procedure was done in the tibia control, without the composite. The animals were daily evaluated for 15 days, assessing the wound dehiscence, lameness, painful sensitivity and the tibia s circumference measured. Radiographs were performed immediately after surgery and 8, 30, 60, 90 and 120 days post-operative characterizing the radioopacity of cortical defect and around the intramedullary pin in both tibias, comparing to the surrounding bone. On the same dates, except on the day of surgery, 4 animals was euthanized and the region of the defect examined: measure of the cortical defect, mechanical traction test of the intramedullar pin, measure the material on the pin threads, medullar canal macroscopic evaluation, X-ray diffraction of the material obtained from the pin thread and the medullar canal, and histological evaluation. Most of the animals had normal clinical development in both groups. In treated group, both radiopacity of the defect and the surface around the pin decreased reaching a similarity to the adjacent bone, while the opposite was observed in the control group, but in this, the area around the pin remained radioluscent until the last observation date. The cortical defect was completely filled by new bone in both groups at the last evaluation date. No significant difference was found between groups for the mechanical traction test, although the values from treated group doubled the control group. Medullar canal macroscopic evaluation in the treated group showed regeneration of bone marrow and visibility loss of the composite on each observation date, almost complete at 120 days, suggesting phagocytosis of the composite. Regeneration of the bone marrow was observed in the control group, since the first day of their assessment. The circumference measures of the material on the threaded surface showed a linear increase with time in both groups, but presented a difference in the 90 and 120 days tissue s characteristic in the group treated: a hard material with macroscopic characteristics of bone. X-ray diffraction showed the evolution on the composite absorption and that the peaks observed in the last two dates presented characteristics consistent with the bone crystalline mineral part. The histological results showed normal bone regeneration in both groups, although the treated groups defect presented an earlier process and the presence of trabecular and compact bone in the medullar canal at the end of the evaluation. It can be concluded that the synthetic hydroxyapatite associated to lignin can guide the process of bone regeneration in the medullar cavity.