Fronto-facial monobloc distraction in syndromic craniosynostosis. Three-dimensional evaluation of treatment outcome and facial growth.

The objectives of this study were to investigate the treatment effect and stability of fronto-facial monobloc distraction osteogenesis. Five consecutive patients who underwent monobloc distraction were included (aged 4.8-18.4 years). Three patients had Crouzon syndrome, one had Apert syndrome, and one had Pfeiffer syndrome. The evaluation included clinical records, serial cephalograms for at least 1-year follow up (average 24.6 months). The treatment and post-treatment changes were measured. The intracranial volume, upper airway volume and globe protrusion were calculated from CT before and after treatment. After distraction, the supraorbital region was advanced 15.3mm forward, the midface demonstrated forward advancement of 17.7 mm, 22.1mm and 23.1mm at orbitale, anterior nasal spine and A point, respectively. The downward movement was 2-3mm at maxillary level. The intracranial volume increased 11%; the upper airway volume increased 85% on average. Globe protrusion reduced 3.7 mm on average, which was 20% of underlying skeletal movement. Facial growth demonstrated forward remodelling of the supraorbital region, mild downward but no further forward growth of the midface. Monobloc distraction is effective for relieving related symptoms and signs through differential external distraction at different vertical levels of the face.