The role of ultrasound in monitoring reconstruction of mandibular continuity defects using osteogenic protein-1 (rhOP-1).

Introducing bone bioengineering concepts in craniofacial surgery demands development of novel imaging strategies, which overcome the shortcomings of radiography such as exposure to ionizing radiation. This study is aimed to investigate the usefulness of ultrasonography (US) in monitoring reconstruction of continuity osteoperiosteal mandibular defects in sheep using rhOP-1. The study was conducted on six adult sheep in which a critical size defect was created at the body of the mandible and was reconstructed using rhOP-1 with type-I collagen as a carrier. Ultrasound images were used to assess onset of bone formation, contour, and surface topography. The results were then compared to corresponding plain radiographs and to post-mortem observations. US showed bone union in all the subjects that concurred with radiographic and post-mortem examinations. US was superior to plain radiography in monitoring early events of ossification. However, it was relatively less efficient in describing the contour of the newly formed bone. It was possible to describe the pattern of bone formation and the dynamic changes in contour and surface topography via US during the follow-up period. In experienced hands, ultrasonography can offer valuable information about bone healing comparable with those obtained by plain radiography. US may replace plain radiography in becoming a routinely used tool for monitoring bone healing in selected sites of the craniofacial skeleton.