Functional Outcomes in Monobloc Advancement by Distraction Using the Rigid External Distractor Device

Background: Craniofacial dysostosis syndromes produce multisutural synostoses combined with severe midfacial retrusion. This may cause serious functional problems, including airway obstruction, exposure of the eyes, visual pathway dysfunction, and raised intracranial pressure. Early midface advancement may be necessary to address these issues. Distraction osteogenesis has provided the facility to achieve significant advances safely and is often in excess of that which is achievable by conventional means. Methods: A retrospective study of 20 patients with craniofacial dysostosis and severe midface hypoplasia who underwent monobloc advancement osteotomies using the rigid external distractor system principally for functional reasons was undertaken. The multidisciplinary management and outcome measures of these patients were recorded. Results: The midface was distracted an average of 16.4 mm, with a range of 12 to 22 mm. Ocular protection was achieved in all patients with preoperative exposure keratopathy and/or globe subluxation. Improvements in optic disc swelling and pattern visually evoked potentials were seen in those patients with threatened visual impairment. Improvement in airway obstruction was seen in those patients with abnormal polysomnography. Decannulation was achieved in five of the seven patients with tracheostomies. Fifty percent had a reduction in hyponasality, and the visual appearance of speech was improved. Complications included persistent cerebrospinal fluid leakage, acquired hypernasality in 25 percent, cranial bone loss, and sinus formation requiring surgical revision. Conclusions: Monobloc distraction osteogenesis results in good aesthetic and functional outcomes. The relatively high rate of complications remains a concern, and further adaptations of technique are needed to reduce the risks of this procedure.