Characterization of cortical bone fracture with scanning confocal ultrasound and longitudinal acoustic velocity

Non-invasive assessment of fracture, particularly in non-typical fracture, is a critical health problem. As a promising alternative to the x-ray, ultrasound has demonstrated potentials in early fracture diagnosis. A real-time scanning confocal ultrasound image was developed to evaluate bone defect and bone loss. The objectives of this study were to evaluate the cortical fracture gap size using quantitative ultrasound imaging and the longitudinal ultrasound velocity in bone to predict the fracture gap size. The total fractures were created by MTE compression at the middle diaphysis, with gap size varied from 1–5 mm (N=4). Fractures were tested with the ultrasound scanning with 0.5-mm resolution. The measured ultrasound signals were analyzed to calculate BUA (dB/MHz), ATT (dB), and transverse velocity (m/s). The longitudinal wave velocity was tested using three surface transducers. Strong correlations were observed between ultrasound and x-ray images in fracture size (R2=0.91). High correlation was found between gap size and the longitudinal velocity from 4000 to 3000-m/s for 0–5-mm gaps (R2=0.93). These results suggest that ultrasound is capable to predict bone fracture and provide useful information for longitudinal assessment of complications, such as non-union fracture, and for evaluating healing. [Work supported by NSBRI/NASA and NIH.]