The use of quantitative ultrasound to monitor fracture healing: a feasibility study using phantoms

Fracture healing has traditionally been monitored subjectively using manual manipulation of the fracture site and evaluation of radiographic images. A more objective method of monitoring would provide obvious advantages, allo wing healing progress to be quantitatively assessed and so providing the op portunity for early detection of problems. A tibia phantom was used to inve stigate whether the longitudinal propagation velocity of ultrasound across a fracture site could be used quantitatively to assess fracture healing. Th e characteristic of fracture healing simulated by the phantom was the chang ing gap between the bone ends at the fracture site. The ultrasound velocity was measured using a recently developed machine, the SoundScan 2000 (Myria d Ultrasound Systems Ltd, Israel). The precision of the SoundScan 2000 was found to be 0.4% in vitro. Ultrasound velocity predicted the simulated frac ture gap with a high degree of accuracy (R-2 = 0.994). The measured and the theoretically calculated velocity for different widths between the simulat ed bone ends was found to be highly correlated with a coefficient of determ ination of 0.998. This result shows that the use of quantitative ultrasound to monitor fracture healing warrants further investigation in vivo. (C) 19 99 IPEM. Published by Elsevier Science Ltd. All rights reserved.