No abstract

Objectives: The objective of this study was to compare the in vitro ultrasonic velocity and attenuation in bone healing evaluation. Methods: Seventeen sheep weighting 37 kg in average were used, being divided into two groups of five animals each and one group of seven animals, according to the postoperative follow-up time (30, 60 and 90 days, respectively). Osteotomies were performed on the right tibiae and the intact left tibiae of the 17 animals were used as control. The healing process was monitored with conventional conventional radiographs taken at two-week intervals. The animals were sacrificed at the end of the corresponding follow-up period and both right and left tibiae were removed for in vitro underwater and contact ultrasound evaluations. The transverse and longitudinal ultrasound propagation velocity (USPV) and the broadband ultrasound attenuation (BUA) were measured and correlated. Results: USPV increased with the progression of the healing process, while BUA decreased, with significant differences between the experimental and control groups and between the experimental groups, for most of the comparisons. Conclusion: It was concluded that the method using ultrasound as employed in this investigation is feasible and reliable for evaluating cortical bone healing.

Ultrasound transmission in human bodies has been studied for several decades in order to facilitate diagnosis. It has also been used to evaluate bone density and to diagnose early osteoporosis and future fracture risks. For this study, a system to generate, receive and amplify ultrasonic signs for speed of sound assessment and broad band ultrasound attenuation (BUA) was developed. Transmission of ultrasonic signals was performed by coupling using ultrasound gel and water (acoustic tank) and the sample placed between two transducers, one for transmission and the other for reception. Due to the high rate of the dispersion of ultrasonic measures, some reference material having the characteristics of the speed of sound and broad band ultrasound attenuation, similar to the heel bone that will be used for equipment calibration and follow-up of bone measure will have to be found. Ultrasonic parameters were used to evaluate bone consolidation (tibia of a sheep), in different periods and several kinds of fractures. Temperature and reproducibility using different materials were used to customize the system. Measures of volunteers's heel bone speed and broad band ultrasound attenuation showed results consistent with the ones from literature. Several analyses with little changes in geometric, signal and transducer frequency conditions were performed in order to observe their influence on attenuation and speed measures. Those steps were carried out in order to try to relate the variations in attenuation measures to those obtained by other authors.

Foi realizado um estudo experimental sobre a avaliação ultra-sonométrica da consolidação de tíbias de carneiros submetidas a osteotomia transversal mediodiafisária, utilizando 15 carneiros, com pêso médio de 37 Kg, divididos em três grupos experimentais de cinco animais cada, conforme o período de observação pós-operatória de 30, 45 e 60 dias. As osteotomias foram realizadas nas tíbias direitas dos animais, ficando as tíbias esquerdas como controle. Foi feita avaliação radiográfica da consolidação a cada duas semanas e, ao fim do período de observação, os animais foram sacrificados e as tíbias, removidas para a análise ultra-sonométrica. Foram medidos e correlacionados o diâmetro da tíbia e a velocidade de propagação transversal do ultra-som na região da osteotomia, em duas direções diferentes (perpendicular e paralela ao plano da tuberosidade anterior da tíbia). A velocidade de propagação do ultra-som aumentou com o avançar da consolidação (±5%), sendo as diferenças significantes em relação ao grupo-controle, mas não entre os grupo experimentais. Os diâmetros diminuíram nas duas direções medidas, sendo as diferenças significantes entre os grupos, com forte correlação negativa com a velocidade. Concluiu-se que o método de avaliação da consolidação pela ultra-sonometria é factível, com resultados confiáveis e precisos.