[Sonography in callus distraction of the hypoplastic mandible]

Since the early 1990's when callus distraction of hypoplastic mandibles was developed, surgeons have been looking for a reliable method to monitor distraction treatment. X-rays films resulted in insufficient quality of images of low calcified structures and are only of little support in follow-up. Therefore, a standardised protocol using ultrasound was introduced.

24 patients were included (aged 4 - 29 years with hemifacial microsomy [19], mandibulary micrognathia [5]), 20 intraoral (Howmedica-Leibinger/Mühlheim) and 9 extraoral distractors (Normed/Tuttlingen). Standard procedures for intra- and extraoral distraction were carried out and all postsurgical treatment steps were monitored by ultrasound.

The mineralisation of the neocallus shows the following sequence: echogenic dots, needles directed along the distraction direction, bands, plaques, and modulation of the neocompacta. Additional therapeutically relevant questions of distraction distance, inflammation or occurrence of pus, arising during treatment were answered by sonography. Distance measurements could be performed reliably. CAT scan and MRI cannot be carried out because of metal artefacts. X-ray pictures like orthopantomogram and Clementschisch projection cannot show the early mineralisation and do not allow an exact distance measurement.

Sonography is a effective, method to investigate the callus field without using X-rays and supports monitoring and decision making in distraction treatment of hypoplastic mandibles.