Sonographic callus may enable assessment of fracture healing. The aim of this study was to establish a reliable method for three-dimensional reconstruction of sonographic callus. Patients that underwent non-operative management of displaced midshaft clavicle fractures and intramedullary nailing of tibia fractures were prospectively recruited and followed to union. Ultrasound scanning was performed at periodical time points following injury. Infra-red tracking technology was used to map each image to a three-dimensional lattice. Criteria was fist established for two-dimensional bridging callus detection in a pilot study. Using echo intensity of the ultrasound image, semi-automated mapping was used to create an anatomic three-dimensional representation of fracture healing. Agreement on the presence of sonographic bridging callus was assessed using the kappa coefficient and intra-class-correlation (ICC) between observers. 112