Orbital aspects following monobloc advancement in syndromic craniosynostosis.

The monobloc advancement with distraction is a treatment modality for syndromic craniosynostosis, to correct exorbitism, upper airway compromise and malocclusion. In this report orbital volume and movements of (peri-)orbital structures and globes of seven patients following monobloc distraction are evaluated. In preoperative and postoperative CT-scans orbital volume was assessed and a 3D coordinate system with eleven landmarks was used to measure the movements of orbital structures and globes and to measure the change of exorbitism. Correlation between orbital volume, movements of the orbital structures and change in exorbitism was studied. The orbital volume increased by 49.9% (left) and 50.4% (right). The average anterior movement of the bone was 13.6 mm (left) and 13.9 mm (right). The mean anterior movement of the left globe was 5.8 mm and of the right globe 5.3 mm. The ratio of globe/bone movement was 0.4. Exorbitism decreased with 7.8 mm (left) and 8.1 mm (right). Differences between left and right for orbital volume, for movements and for the decrease in exorbitism were not significant. Volume enlargement and decrease in exorbitism were correlated (p ≤ 0.05). Following monobloc advancement orbital volume increases, (peri-)orbital structures and the globe move forward and exorbitism diminishes.