Regardless of its type, the repair of a peripheral nerve must ideally permit early motion of the affected limb and resist disruption by the tensile forces generated throughout the healing process and regeneration. A comparative study of the mechanical resistance of the repair of the sciatic nerve with biological glue and conventional microsurgical suture over time was undertaken in 48 rats. Both right and left sciatic nerves were exposed simultaneously and repaired at random with the glue on one side and conventional suture on the opposite side. Mechanical resistance of the repair was evaluated in situ with a universal testing machine using a hooklike accessory applied proximally to the repair site, immediately and at 7, 14, and 28 days postoperatively. A load was applied at the rate of 2 mm/min till rupture. The resistance of both types of repair significantly increased up to day 14 ( P < 0.001), and the repair with the glue was significantly less resistant than repair with conventional suture immediately postoperatively ( P < 0.001) and on day 7 ( P = 0.03). Resistance became equivalent for the two types of repair on days 14 ( P = 0.67) and 28 ( P = 0.34). The change in resistance of both types of repair with time was in accordance with the power function numeric formula.
Este trabalho teve como objetivo estudar as alterações microvasculares intraneurais aguda em nervo isquiático de rato submetido a esmagamento por diferentes cargas. Foram utilizados 60 ratos machos da linhagem Wistar, distribuídos em grupos experimentais de acordo com a injeção de vasos e com a carga de esmagamento. Os nervos isquiáticos direitos foram isolados e submetidos ao esmagamento com cargas (0,5 Kg, 1 Kg, 5 Kg, 10 kg e 15 kg) por 10 minutos e os nervos isquiáticos esquerdos foram utilizados como controle. Após esmagamento, os animais foram submetidos à cateterização da aorta abdominal e injeção dos vasos, em seguida 30 nervos direitos e esquerdos foram fixados em formol 10%, desidratados e diafanizados para análise longitudinal dos vasos intraneurais e os restantes retirados em toda a sua extensão, cortados em 3 fragmentos, congelados em isopentano em gelo seco e armazenados em freezer -70°C, seccionados transversalmente para análise e contagem dos vasos intraneurais. As análises macroscópica e microscópica mostraram regiões de hematoma endoneural e epineural nas diferentes cargas de esmagamento. A análise morfométrica sugere que a lesão aos vasos intraneurais foi proporcional à carga de esmagamento, causando hematoma endoneural e epineural, que cria microambiente desfavorável para a regeneração das fibras nervosas.
PURPOSE:To evaluate the effects of torsional force on the rotational axis of living lamb tibias.
METHODS:An external fixator device was designed to apply rotation to the tibias of lambs. Once a week, the bone distal extremity was rotated 2º. After achieving ~20º of internal rotation, the turning was discontinued and the device was maintained in situ for one month and euthanasia occurred in group A (n=10) after this. In group B (n=9) euthanasia occurred three months after removing the device.Computed tomography scans evaluated the rotational angle; dual-energy X-ray absorptiometry assessed the bone mineral density, and conventional and polarized light microscopy studied the bone microstructure.
RESULTS:In group A, the mean angle of the external rotation in the control tibias was 24º and 8º in the twisted tibias (p<0.0001); in group B, the angle was 23º (control) and 7º (twisted, p<0.0001), with no differences between groups A and B (p=0.9567). The BMD increased in the twisted tibias in group A (p<0.0001) and in group B (p=0.0023), with no between-group differences (p>0.05).Microscopically, the twisted tibias showed asymmetrical subperiosteal bone deposition on the lateral cortex surface.
CONCLUSION:Gradual torsion applied to the immature tibia significantly modified its rotational axis.
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