Characterization of pseudarthrosis with ultrasound backscattered signals in rats

Abstract

Purpose:To propose a novel model of pseudarthrosis in a small animal and to investigate the ability of backscatter parameters from ultrasound signals in differentiating normal bone from those ones with pseudarthorsis. Methods: Twelve Rattus norvegicus albinus free from pathogenic species (SPF) were randomly divided in two groups, with six animals each. In the Control group a surgical approach to the femur was made, followed by the synthesis of the muscle and skin layers. The Experimental group was submitted to an osteotomy of the femur and a vascularized flap of the fascia lata was interposed in the line of the fractured bone. Then the alignment and bone stabilization were accomplished, by using nylon stitch in U shape introduced in holes made in the proximal and distal fractured bone. Bone samples were scanned with ultrasound and signals were collected for each one to analyze the parameter Apparent Integrated Backscatter -AIB. Results: Radiological and anatomopathologic studies revealed the absence of bone consolidation with persistence of fiber-osteoid tissue. Values of the ultrasound parameter AIB from normal bones were statistically different from those with pseudarthrosis. Conclusion: The experimental model was suitable for pseudarthrosis development in rats and the ultrasound backscatter parameters were able to identify such a bone disease in vitro. Key words: Disease Models. Animal. Orthopedics. Ultrasonography. Rats. RESUMOObjetivo: Propor um novo modelo de pseudoartrose em animais de pequeno porte e investigar o potencial de parâmetros de retroespalhamento de ultrassônico em diferenciar osso normal e com pseudoartrose. Métodos: Doze Rattus norvegicus albinus (SPF) foram distribuídos aleatoriamente em dois grupos, tendo cada grupo seis animais. No grupo Controle realizou-se uma abordagem cirúrgica ao fêmur, seguida da síntese por planos do músculo e da pele. O grupo Experimental foi submetido à osteotomia do fêmur aduzida da confecção de um retalho pediculado de fascia lata para interposição entre os segmentos resultantes da fratura induzida cirurgicamente. Prosseguiu-se com o alinhamento e estabilização óssea, mediante a confecção de um nó com fio de náilon em formato de U, introduzido em orifícios efetuados nas extremidades proximal e distal à fratura. As amostras ósseas foram irradiadas pelo ultrassom e sinais foram coletados para cada uma no intuito de analisar o parâmetro Retroespalhamento Integrado Aparente -AIB. Resultados: Estudos radiológicos e anatomopatológicos evidenciaram a ausência de consolidação óssea com persistência de tecido fibro-osteóide. Os valores de AIB para ossos normais foram estatisticamente diferentes em relação aos ossos com pseudoartrose. Conclusão: O modelo experimental apresentou-se adequado para a formação de pseudoartrose em ratos e o parâmetro de retroespalhamento de ultrassom foi capaz de detectar tal doença óssea, in vitro. Descritores: Modelos Animais de Doenças. Ortopedia. Ultrassonografia. Ratos

Ultrasonic evaluation of intact, healing and osteoporotic long bones

“…Concerning the early detection of complications, we showed in (Protopappas et al 2005) that the velocity across bones which finally reached bony union was higher than for those with complications even from the 50 th postoperative day. Additionally, the study of (Ferreira et al 2010) on pseudarthrosis in rats showed that AIB values for pseudarthrosis were higher comparing to intact bone. This tendency was attributed to the complex matrix composition of fibrous tissue, cartilage and calcified points with different acoustic impedance.…”

“…Ultrasonic measurements were performed at 0.5 and 1 MHz and higher correlation coefficients were found at 1 MHz. More recently, in Ferreira et al (2010), the ability of ultrasound backscatter parameters in differentiating normal bones from bones with pseudarthorsis was investigated. A diaphyseal osteotomy of the femur was conducted for twelve young adult rats.…”

“…In Section 2, the experimental study of (Ferreira et al 2010) was described in which the backscattering method was used to discriminate normal bone from bone with pseudarthrosis. More recently in (Potsika et al 2016b), we presented simulations of ultrasound propagation in healing long bones using the BEM to investigate the monitoring potential of backscattering parameters.…”

Heterologous mesenchymal stem cells successfully treat femoral pseudarthrosis in rats

“…A reliable model of hypertrophic pseudarthrosis in animals that was previously developed by the authors was able to mimic the conditions found in human beings [9,23]. Pseudarthrosis was detected in all animals within an acceptable period, without the presence of infectious foci.…”