Experimental and simulation results on the effect of cortical bone mineralization in ultrasound axial transmission measurements: a model for XXXX healing ultrasound monitoring.

@entity291 @entity174 @entity460 @entity1054 @entity1098
Ultrasound axial transmission (UAT), a technique using propagation of ultrasound waves along the cortex of cortical bones, has been proposed as a diagnostic technique for the evaluation of @entity174 healing. Quantitative ultrasound parameters have been reported to be sensitive to callus changes during the regeneration process. The aim of this work was to identify the specific effect of cortical bone mineralization on UAT measurements by means of numerical simulations and experiments using a reverse @entity174 healing approach. A cortical @entity291 femur sample was used, in which a 3mm @entity174 gap was drilled. A 3mm thick cortical bone slice, extracted from another location in the bone sample, was submitted to a progressive demineralization process with @entity1098 during 12 days. UAT measurements and simulations using a 1MHz probe were performed with the demineralized slice placed into the @entity174 gap to mimic different stages of mineralization during the healing process. The @entity460 loss of the slice due to the @entity1098 treatment was recorded everyday, and its temporal evolution could be modeled by an exponential law. A 50MHz scanning acoustic microscopy was also used to assess the mineralization degree of the bone slice at the end of the intervention. These data were used in the numerical simulations to derive a model of the time evolution of bone slice mechanical properties. From both the experiments and the simulations, a significant and progressive increase in the @entity1054 ( @entity1054 ; p<0.001) of the propagating waves measured by UAT was observed during the beginning of the demineralization process (first 4 days). Although the simulated @entity1054 values were slightly larger than the experimental ones, they both exhibited a similar time-dependence, validating the simulation approach. Our results suggest that @entity1054 measured in axial transmission is affected by local changes of speed of sound induced by changes in local mineralization. @entity1054 may be an appropriate indicator to monitor callus maturation.
