Compósitos de hidroxiapatita e polihidroxibutirato em defeitos ósseos experimentais na ulna de coelhos
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2007-10-29
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Universidade Federal de Viçosa
Resumo
Os biomateriais hoje utilizados no tratamento das fraturas ósseas e da perda do tecido ósseo ainda apresentam deficiências a serem corrigidas. O presente trabalho consta da análise preliminar de características essenciais para utilização de compósitos de hidroxiapatita (HAP-91®) e polihidroxibutirato (PHB) em ortopedia. Estudou-se a biocompatibilidade, osseointegração, osseocondução e biodegradação dos compósitos em defeitos ósseos. Foram implantados três compósitos fabricados com diferentes proporções desses biomateriais em defeitos circulares bilaterais no olécrano de 30 coelhos, onde cada membro recebeu um compósito, com um total de 12 membros por grupo. Os membros do grupo 1 receberam compósitos contendo 10% de HAP-91® e 90% de PHB, do grupo 2 contendo 25% de HAP-91® e 75% de PHB, do grupo 3, 50% de cada biomaterial e os animais do grupo controle não receberam compósito. Os membros foram avaliados quanto à claudicação, circunferência do membro, sensibilidade dolorosa, deiscência e infecção nos oito primeiros dias após a cirurgia e aos 45 e 90 dias. Foram radiografados imediatamente após a cirurgia e aos oito, 45 e 90 dias. Nessas mesmas datas, 4 animais de cada grupo foram eutanasiados, coletando-se material para processamento histológico. Existiu diferença significante entre os valores de circunferência do membro no pré-operatório e do primeiro dia após a cirurgia dentro de todos os grupos, o que não ocorreu em relação aos dias quatro e oito. Não houve diferença entre os grupos para esse parâmetro assim como para os demais. Não foi observado contato direto entre osso e compósito nas radiografias obtidas aos oito dias após as cirurgias, mas aos 45 e 90 dias nos três grupos tratados observou-se este contato. À análise histológica do grupo controle observou-se processo típico de reparação, ou seja, tecido conjuntivo denso vascularizado e trabéculas ósseas novas aos oito dias com evolução para osso trabecular mais organizado aos 90 dias e cortical lateral restabelecida. Os tecidos observados nos grupos 1, 2 e 3 foram semelhantes ao controle, sendo a proporção de tecido ósseo formada no defeito, maior do que a de tecidos moles em todas as datas. Nos grupos dois e três foram observadas projeções de tecido ósseo e conjuntivo no interior dos poros do compósito. Infiltrados inflamatórios não foram observados em nenhum momento. O grupo 3 apresentou interface com maior proporção de tecido ósseo formado na região do defeito e no interior do compósito do que os grupos 1 e 2. Observou- se osteoclastos nas bordas dos compósitos e fragmentos dos mesmos separados do bloco principal aos 45 e 90 dias nos três grupos. Concluiu-se que os compósitos são biocompatíveis, osteocondutores, se integram ao tecido ósseo e são degradados in vivo.
Biomaterials used today to treat bones' defects and fractures still bear some deficiencies to be corrected. This study is a preliminary analysis of composites' made of hydroxyapatite (HAP-91®) and polyhydroxybutyrate (PHB) essentials characteristics to be used in orthopedics. The composites were studied in osseous defects concerning their biocompatibility, osseointegration, osseoconduction, and biodegradation. Bone defects were made bilaterally in the olecranon of 30 white rabbits and each filled with a composite, with a total of 12 members per group. Limbs in the 1 group received composite # 1: 10% of HAP-91® and 90% of PHB; limbs in 2 group received composite # 2: 25% HAP- 91® and 75% PHB; and in 3 group the composite # 3: 50% of each biomaterial. Defects in the control group were not filled. Limbs were evaluated in the first eight days after surgery and again at 45 and 90 days afterwards for lameness, circumference, pain, dehiscence, and infection. Radiographs were taken 8, 45 and 90 days after surgeries when four animals in each group were euthanized and samples with defects taken for histology. Significant differences in circumference data were found for all groups before and one day after surgery, what did not happen with four and eight days. No significant differences were found between groups for circumference as well as for the other clinical parameters. Radiographs taken 8 days after surgery showed no bone- composite apposition, but those for the 45th and 90th days after showed that composites were in direct contact with bone. Histological observations indicated a normal repair process in the 8th day, i.e., a vascularized, dense connective tissue and new, early trabecular bone; this evolved to fully organized trabecular bone and the lateral cortical completely formed by the 90th-day. At the three observation dates, tissues in 1, 2, and 3 group samples were found similar to those in control, where more bone than soft tissues were found in the defect. Projections of connective and bone tissues were seen inside composites #2 and 3. No inflammatory cells in any place whatsoever were found at any observation date. Clearly more bone built up in 3 samples, and at its interface, than in the 1 and 2 groups samples. At the 45 and 90th days, in all three groups, osteoclasts were seen in the bone-composite interface, and also composite pieces, detached from the original block, were found within the bone structure and surrounding soft tissues. Conclusion is that the composites are biocompatible, osseoconductive, integrate to bone and can undergo in vivo degradation.
Biomaterials used today to treat bones' defects and fractures still bear some deficiencies to be corrected. This study is a preliminary analysis of composites' made of hydroxyapatite (HAP-91®) and polyhydroxybutyrate (PHB) essentials characteristics to be used in orthopedics. The composites were studied in osseous defects concerning their biocompatibility, osseointegration, osseoconduction, and biodegradation. Bone defects were made bilaterally in the olecranon of 30 white rabbits and each filled with a composite, with a total of 12 members per group. Limbs in the 1 group received composite # 1: 10% of HAP-91® and 90% of PHB; limbs in 2 group received composite # 2: 25% HAP- 91® and 75% PHB; and in 3 group the composite # 3: 50% of each biomaterial. Defects in the control group were not filled. Limbs were evaluated in the first eight days after surgery and again at 45 and 90 days afterwards for lameness, circumference, pain, dehiscence, and infection. Radiographs were taken 8, 45 and 90 days after surgeries when four animals in each group were euthanized and samples with defects taken for histology. Significant differences in circumference data were found for all groups before and one day after surgery, what did not happen with four and eight days. No significant differences were found between groups for circumference as well as for the other clinical parameters. Radiographs taken 8 days after surgery showed no bone- composite apposition, but those for the 45th and 90th days after showed that composites were in direct contact with bone. Histological observations indicated a normal repair process in the 8th day, i.e., a vascularized, dense connective tissue and new, early trabecular bone; this evolved to fully organized trabecular bone and the lateral cortical completely formed by the 90th-day. At the three observation dates, tissues in 1, 2, and 3 group samples were found similar to those in control, where more bone than soft tissues were found in the defect. Projections of connective and bone tissues were seen inside composites #2 and 3. No inflammatory cells in any place whatsoever were found at any observation date. Clearly more bone built up in 3 samples, and at its interface, than in the 1 and 2 groups samples. At the 45 and 90th days, in all three groups, osteoclasts were seen in the bone-composite interface, and also composite pieces, detached from the original block, were found within the bone structure and surrounding soft tissues. Conclusion is that the composites are biocompatible, osseoconductive, integrate to bone and can undergo in vivo degradation.
Descrição
Palavras-chave
Hidroxiapatita, Polihidroxibutirato, Biomaterial, Regeneração óssea, Hydroxyapatite, Polyhydroxybutyrate, Biomaterials, Bone regeneration
Citação
REIS, Emily Correna Carlo. Hydroxyapatite-polyhydroxybutyrate composites in experimentally made bone deffects in rabbits ulna. 2007. 71 f. Dissertação (Mestrado em Biotecnologia, diagnóstico e controle de doenças; Epidemiologia e controle de qualidade de prod. de) - Universidade Federal de Viçosa, Viçosa, 2007.