A critical size defect model in the radius of rabbits / Modelo de falha óssea segmentar em rádio de coelhos

This study aimed to characterize a preclinical model of critical size defect (CSD) in the radius of rabbits.Twenty adults (> 7 months), female, New Zealand Rabbits, weighing between 3,5 to 5 Kg were used. They underwent a 1.5 cm long ostectomy of the diaphysis of the radius, starting 2 cm from the carpus joint. Radiographic analyses were performed at 15, 30, 60, and 90 days postoperatively, in order to evaluated bone callus formation, periosteal reaction, and bone bridge formation.The methodology allowed to precisely create bone defects of 1.5cm. Over time, no bone deposition was found at 15 days, but mild bone callus formation was observed in three animals after 60 days postoperative. At 90 days postoperatively only one rabbit presented bone consolidation radiographically, the others presented non-union. The critical bone defect proposed in this study was satisfactory, feasible with very low risk of complications.(AU)

O objetivo do presente estudo é caracterizar um modelo pré-clínico de falha óssea crítica em rádio de coelhos. Vinte coelhos adultos (> 7 meses), fêmeas, da raça New Zealand, pesando entre 3,5 e 5 kg foram utilizados. Os animais foram submetidos à ostectomia segmentar de 1,5 cm na diáfise do rádio, iniciando 2 cm acima da articulação carpo radial. As análises radiográficas foram feitas aos 15, 30, 60 e 90 dias pós-operatório, para avaliação de formação de calo ósseo, reação periosteal e formação de ponte óssea. nA metodologia permitiu a criação precisa de defeitos ósseo segmentar de 1,5 cm. Durante o experimento, não se observou deposição óssea na primeira avaliação radiográfica, porém após 60 dias foi possível visibilizar formação de calo ósseo em 3 animais. Aos 90 dias apenas um animal apresentou consolidação óssea radiograficamente; o restante apresentou não-união óssea. A falha óssea foi eficaz para estabelecer um defeito ósseo crítico além de apresentar fácil aplicação, apresentando pequeno índice de complicação.(AU)

A critical size defect model in the radius of rabbits / Modelo de falha óssea segmentar em rádio de coelhos

This study aimed to characterize a preclinical model of critical size defect (CSD) in the radius of rabbits.Twenty adults (> 7 months), female, New Zealand Rabbits, weighing between 3,5 to 5 Kg were used. They underwent a 1.5 cm long ostectomy of the diaphysis of the radius, starting 2 cm from the carpus joint. Radiographic analyses were performed at 15, 30, 60, and 90 days postoperatively, in order to evaluated bone callus formation, periosteal reaction, and bone bridge formation.The methodology allowed to precisely create bone defects of 1.5cm. Over time, no bone deposition was found at 15 days, but mild bone callus formation was observed in three animals after 60 days postoperative. At 90 days postoperatively only one rabbit presented bone consolidation radiographically, the others presented non-union. The critical bone defect proposed in this study was satisfactory, feasible with very low risk of complications.

O objetivo do presente estudo é caracterizar um modelo pré-clínico de falha óssea crítica em rádio de coelhos. Vinte coelhos adultos (> 7 meses), fêmeas, da raça New Zealand, pesando entre 3,5 e 5 kg foram utilizados. Os animais foram submetidos à ostectomia segmentar de 1,5 cm na diáfise do rádio, iniciando 2 cm acima da articulação carpo radial. As análises radiográficas foram feitas aos 15, 30, 60 e 90 dias pós-operatório, para avaliação de formação de calo ósseo, reação periosteal e formação de ponte óssea. nA metodologia permitiu a criação precisa de defeitos ósseo segmentar de 1,5 cm. Durante o experimento, não se observou deposição óssea na primeira avaliação radiográfica, porém após 60 dias foi possível visibilizar formação de calo ósseo em 3 animais. Aos 90 dias apenas um animal apresentou consolidação óssea radiograficamente; o restante apresentou não-união óssea. A falha óssea foi eficaz para estabelecer um defeito ósseo crítico além de apresentar fácil aplicação, apresentando pequeno índice de complicação.

Development of a bone nonunion in a noncritical segmental tibia defect model in sheep utilizing interlocking nail as an internal fixation system.

BACKGROUND: The bone nonunion is an important complication of bone fracture repair. The existing models developed on small animal species prevent using osteosynthesis materials designed to be implanted in human bones. The goal of this study was to develop a nonunion process in a noncritical segmental tibial defect in sheep, a species analogous in size to humans. MATERIALS AND METHODS: The animals were divided into two groups of four animals each. In Group 1 (experimental), the defect was created by surgically stripping the periosteum from the edges of a distal tibial osteotomy, keeping the edges 5 mm apart, and placing an incomplete O-shaped silicone ring in the gap. Group 2 (control) was intervened with a simple fracture at the distal end of the tibia. In both groups an interlocking nail was used as a fixation system. Over 8 wk after surgery, radiographs and histologic and histomorphometric analyses were performed. RESULTS: The control group showed a typical bone repair process. In contrast, the experimental group showed a fracture line with rounded edges and a scarce callus formation. The bone callus showed reduced amount of bone formation and large content of fibrous tissue (P=0.001). CONCLUSIONS: These results indicate that our model developed an atrophic nonunion in sheep, a species having multiple similarities to humans, such as weight, size, bone structure, and bone remodeling process.

Mistura de proteínas morfogenéticas ósseas, hidroxiapatita, osso inorgânico e colágeno envolta por membrana de pericárdio no preenchimento de defeito ósseo segmentar em coelhos / Mixture of bone morphogenetic protein, hydroxyapatite, inorganic bone and collagen interposed by pericardium barrier membrane in the filling of the segmental bone defect in rabbits

Avaliou-se o uso de biomaterial de origem bovina na regeneração de defeitos ósseos segmentares empregando-se 12 coelhos, fêmeas, da raça Norfolk, com idade de seis meses e pesos entre 3 e 4,5kg. Realizou-se falha segmentar bilateral de um centímetro de comprimento na diáfise do rádio, com inclusão do periósteo. No membro direito, o defeito foi delimitado por membrana de pericárdio liofilizada, contendo em seu interior mistura de proteínas morfogenéticas ósseas adsorvidas a hidroxiapatita, colágeno liofilizado e osso inorgânico. No membro esquerdo, o defeito não recebeu tratamento. Radiografias foram obtidas ao término do procedimento cirúrgico e aos sete, 30, 60, 90, 120 e 150 dias de pós-operatório. Após eutanásia de seis coelhos aos 60 dias e seis aos 150 dias de pós-cirúrgico, os resultados radiográficos e histológicos mostraram que a regeneração óssea foi inibida nos defeitos segmentares tratados com o biomaterial.(AU)

Biomaterials of bovine origin in regenerating segmental bone defects were evaluated. Twelve six-month old Norfolk rabbits, weighting 3 to 4.5kg were used. A 1cm long segmental defect was created in the radial diaphysis, including the periosteum, of both forelimbs. In the right forelimb, the defect was filled using a mixture of bone morphogenic proteins adsorbed to hydroxyapatite, agglutinant of lyophilized collagen in granules and anorganic cortical bone in granules delimited by a pericardial membrane. In the left forelimb, the defect did not receive treatment and served as a control. Radiographies were taken immediately after surgery and at seven, 30, 60, 90, 120 and 150 days post-operatively. Six rabbits were euthanized at 60 days and the other six at 150 days post-surgery for histological evaluation. Radiographic and histological results revealed that bone regeneration was inhibited in the segmental defects receiving biomaterials.(AU)