Avaliação biomecânica da técnica de sobreperfuração da cortical óssea cis em placas bloqueadas com sistema de bloqueio cônico aplicadas em modelo de fratura femoral de coelhos
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Data
2022-06-10
Autores
Pereira, Geovane José
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo do estudo foi avaliar a influência da técnica de sobreperfuração da cortical óssea nas propriedades mecânicas da montagem composta de placa bloqueada, com sistema de bloqueio cônico, em modelo de fratura transversa femoral de coelhos. Foram utilizados sete pares de fêmures de coelhos, com idade estimada em seis meses. Após descongelação dos ossos, estes foram divididos em dois grupos: Grupo 1 – controle (n=7); Grupo 2 – sobreperfuração (n=7). Foram utilizadas placas bloqueadas de aço inoxidável compostas de cinco orifícios com buchas rosqueáveis de titânio. No Grupo 1 parafusos bicorticais foram aplicados nos orifícios 1, 2, 4 e 5. No Grupo 2 as placas foram aplicadas de forma semelhante ao Grupo 1, porém aplicou-se os parafusos com sobreperfuração da cortical óssea cis. Após a colocação da placa e parafusos foi criada uma fratura transversa de 2 mm de comprimento. Foram realizados ensaios de compressão com carga axial distribuída excentricamente, com velocidade de 5 mm/minuto e célula de carga de 500 kgF. A média da força máxima foi estatisticamente maior no Grupo 2 comparada ao Grupo 1, porém a inclinação foi similar entre os grupos. As falhas das montagens do Grupo 1 ocorreram em sua maioria por fissura, principalmente entre os parafusos proximais, ao passo que no Grupo 2 não ocorreu um padrão definido. Foi possível concluir, que pelo ensaio mecânico destrutivo com carregamento estático a sobreperfuração da cortical cis promoveu um aumento da força máxima suportada pela montagem, porém sem alteração na rigidez.
This study aimed to evaluate the influence of the near-cortical over-drilling technique on the biomechanical properties of the locking plate constructs with a conical locking in the rabbit femoral transverse fracture model. Seven pairs of femurs from rabbits presenting six months of age were used. After thawing the bones, they were divided into two groups: Group 1 – control (n=7); Group 2 – over-drilling (n=7). Locked stainless-steel plates composed of five holes with titanium bushings were used. In Group 1, bicortical screws were applied in holes 1, 2, 4, and 5. In Group 2, plates were applied similarly to Group 1, but screws were placed using the near-cortical over-drilling technique. After placement of the plate and screws, a transverse fracture with a 2 mm gap was created. Compression test was carried out with axial load applied eccentrically to the femoral head, at a rate of 5 mm/min and a load cell of 500 kg/F. The mean value of the maximum load was statistically higher in Group 2 compared to Group 1, but the stiffness value was similar between the groups. The failures of the constructs in Group 1 mostly occurred due to cracking, mainly between the proximal screws, while there was no defined pattern in Group 2. In conclusion, the destructive mechanical test with static loading, the over-drilling of the near cortical promoted an increase of maximum load supported by the constructs, but without differences in stiffness.
This study aimed to evaluate the influence of the near-cortical over-drilling technique on the biomechanical properties of the locking plate constructs with a conical locking in the rabbit femoral transverse fracture model. Seven pairs of femurs from rabbits presenting six months of age were used. After thawing the bones, they were divided into two groups: Group 1 – control (n=7); Group 2 – over-drilling (n=7). Locked stainless-steel plates composed of five holes with titanium bushings were used. In Group 1, bicortical screws were applied in holes 1, 2, 4, and 5. In Group 2, plates were applied similarly to Group 1, but screws were placed using the near-cortical over-drilling technique. After placement of the plate and screws, a transverse fracture with a 2 mm gap was created. Compression test was carried out with axial load applied eccentrically to the femoral head, at a rate of 5 mm/min and a load cell of 500 kg/F. The mean value of the maximum load was statistically higher in Group 2 compared to Group 1, but the stiffness value was similar between the groups. The failures of the constructs in Group 1 mostly occurred due to cracking, mainly between the proximal screws, while there was no defined pattern in Group 2. In conclusion, the destructive mechanical test with static loading, the over-drilling of the near cortical promoted an increase of maximum load supported by the constructs, but without differences in stiffness.
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Palavras-chave
Osso, Imobilização, Fixação interna, Carga axial, Bone