Volumetric Changes in Cranial Vault Expansion: Comparison of Fronto-Orbital Advancement and Posterior Cranial Vault Distraction Osteogenesis

Background: Posterior cranial vault distraction osteogenesis has recently been introduced to treat patients with multisuture syndromic craniosynostosis and is believed to provide greater gains in intracranial volume. This study provides volumetric analysis to determine the gains in intracranial volume produced by this modality. Methods: This was a two-center retrospective study of preprocedure and postprocedure computed tomography scans of two groups of 15 patients each with syndromic multisuture craniosynostosis treated with either fronto-orbital advancement or posterior cranial vault distraction osteogenesis. Scan data were analyzed volumetrically with Mimics software. Volumetric gains attributable to growth between scans were controlled for. Results: The mean advancements were 12.5 mm for fronto-orbital advancement and 24.8 mm for distraction osteogenesis. The mean difference in volume between the preoperative and postoperative scans was 144 cm³ for fronto-orbital advancement and 274 cm³ for (p = 0.009). After controlling for growth, the corrected mean volume difference was 66 cm³ for fronto-orbital advancement and 142 cm³ for distraction osteogenesis (p = 0.0017). The corrected mean volume difference per millimeter of advancement was 4.6 cm³ for fronto-orbital advancement and 5.8 cm³ for distraction (p = 0.357). Conclusions: In this retrospective study, posterior cranial vault distraction osteogenesis provided statistically greater intracranial volume expansion than fronto-orbital advancement. The volume gains per millimeter advancement were similar between groups, with a trend toward greater gains per millimeter with distraction osteogenesis. Gradual expansion of the overlying soft tissues with posterior cranial vault distraction osteogenesis appears to be the primary mechanism for greater volume gains with this technique.