Study on the effect of physical loading on bone broadband ultrasound attenuation

Background: Physical loading changes bone microstructure and may influence quantitative ultrasound (QUS) parameters. This in vitro study aims at evaluates the effect of physical loading on bone QUS measurement. Objective: Ten fresh bovine bone specimens were studied. Specimens were scanned by a micro-CT and the density and structure parameters of specimens were calculated. The QUS measurement was performed when specimens subjected to loading, which changed from 0N to 1000N with the step of 100N. Statistical analysis performed to evaluate the difference between nBUA measured with and without loading, and the relationship between nBUA and the parameters measured by micro-CT. Results: While the loading exerted on bone higher than 200N, the measured nBUA significantly higher than nBUA measured without loading. Accompany with the increasing of loading, which exerted on bone, the values of nBUA also increased. A new parameter, the slope of the linearity fitted curve of nBUA values measured under different loading condition, was introduced to evaluate BMD. The correlation coefficient between the slope and BMD is -0.869 (P=0.001). Conclusions: Physical loading substantially influences bone QUS measurement. QUS measurement performed under loading condition may be a new ultrasound method for osteoporosis diagnosis.