Characterization of pseudarthrosis with ultrasound backscattered signals in rats.

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 pseudarthrosis. 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.