Influência da técnica de sobreperfuração da cortical cis nas propriedades mecânicas de placas bloqueadas aplicadas no fêmur de lobos-guará
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Data
2020-07-17
Autores
Siqueira, Rafael Cerântola [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O estudo teve por objetivo avaliar a influência da técnica de sobreperfuração da cortical cis nas propriedades mecânicas de placas bloqueadas aplicadas no fêmur de lobos-guará. Foram empregados nove pares de ossos do fêmur de lobos-guará (Chrysocyon brachyurus) adultos, os quais foram distribuídos por sorteio em quatro grupos. Em todos os grupos foi aplicada uma placa bloqueada de 3,5 mm, manufaturada em aço inoxidavél, compostas de 12 orifícios combinados e um exclusivamente rosqueado, na superfície lateral do fêmur. No G1 (n=4) os parafusos bloqueados bicorticais foram aplicados nos orifícios de números 1, 3, 5, 8, 10 e 12. No G2 (n=5), a placa foi aplicada de forma similar e com a mesma configuração numérica dos parafusos do G1. Contudo, esses foram aplicados pela técnica de sobreperfuração da cortical cis. No G3 (n=5) foi também aplicada a técnica de sobreperfuração da cortical cis, como aplicada no G2, porém foram incluídos os orifícios de números 1, 2, 3, 4, 5, 8, 9, 10, 11 e 12. No G4 (n=4), a placa foi aplicada de forma similar e com a mesma configuração numérica dos parafusos do G2, porém o tamanho da sobreperfuração da cortical cis foi maior. Os orifícios combinados 6 e 7 foram mantidos sobre a área da falha segmentar (1 cm), sem parafuso. As montagens foram analisadas por ensaio estático de flexo-compressão (carga axial excêntrica) até a falência. Foram observadas diferenças estatísticas da força máxima, sendo G4>G1, G4>G2, G3>G1 e G3>G2, bem como na deflexão, sendo G2>G1 e G2>G4. Foi possível concluir que o uso da técnica sobreperfuração cortical aplicada em fratura instável induzida no fêmur de lobos-guará mostrou por ensaio estático de carga axial que a rigidez da montagem não se alterou, mas permitiu alteração na força máxima e deflexão na dependência do tamanho do orifício induzido na cortical cis.
This study aimed to evaluate the influence of the near-cortical over-drilling holes on the mechanical behavior of locking plate constructs applied in maned wolf’s femur. Nine pairs of femur bones of adult maned wolves (Chrysocyon brachyurus) were used, which were randomly distributed into four groups. In all groups, a 3.5 mm locking compression plate, manufactured in stainless steel, designed with 12 combi holes and one exclusively locked, was applied to the lateral surface of the femur. G1 (n=4) received bicortical locking screws placed in holes 1, 3, 5, 8, 10 and 12. In G2 (n=5) the plate was applied as used in G1, but the application of the locked screws involved the near-cortical overdrilling technique. For G3 (n=5), the near-cortical overdrilling technique was also used, but the locked screws were placed in holes 1, 2, 3, 4, 5, 8, 9, 10, 11 and 12. In G4 (n=4) the plate was applied as used in G2, but the size of near-cortical overdrilling was larger. The combi holes 6 and 7 were maintained over 10 mm fracture gap without screws. All constructs were tested to failure in axial load. The axial load was applied eccentrically to the femoral head. Statistical differences were observed in the maximum load with G4>G1, G4>G2, G3>G1, and G3>G2, and in the deflection with G2>G1 and G2>G4. In conclusion, near-cortical overdrilling technique used in unstable fracture induced in the maned wolf's femur showed by static axial compression test that stiffness of constructs did not change, but allowed changes in maximum load and deflection depending on drill hole size induced in near cortex.
This study aimed to evaluate the influence of the near-cortical over-drilling holes on the mechanical behavior of locking plate constructs applied in maned wolf’s femur. Nine pairs of femur bones of adult maned wolves (Chrysocyon brachyurus) were used, which were randomly distributed into four groups. In all groups, a 3.5 mm locking compression plate, manufactured in stainless steel, designed with 12 combi holes and one exclusively locked, was applied to the lateral surface of the femur. G1 (n=4) received bicortical locking screws placed in holes 1, 3, 5, 8, 10 and 12. In G2 (n=5) the plate was applied as used in G1, but the application of the locked screws involved the near-cortical overdrilling technique. For G3 (n=5), the near-cortical overdrilling technique was also used, but the locked screws were placed in holes 1, 2, 3, 4, 5, 8, 9, 10, 11 and 12. In G4 (n=4) the plate was applied as used in G2, but the size of near-cortical overdrilling was larger. The combi holes 6 and 7 were maintained over 10 mm fracture gap without screws. All constructs were tested to failure in axial load. The axial load was applied eccentrically to the femoral head. Statistical differences were observed in the maximum load with G4>G1, G4>G2, G3>G1, and G3>G2, and in the deflection with G2>G1 and G2>G4. In conclusion, near-cortical overdrilling technique used in unstable fracture induced in the maned wolf's femur showed by static axial compression test that stiffness of constructs did not change, but allowed changes in maximum load and deflection depending on drill hole size induced in near cortex.
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Palavras-chave
Placa metálica, Parafuso, Fratura, Canídeo, Animal selvagem, Bone plate, Screw, Fracture, Canid, Wild animal