A Craniometric Analysis of Frontal Cranial Morphology Following Posterior Vault Distraction

BACKGROUND: Posterior vault distraction osteogenesis (PVDO) is believed to improve frontal contour in infants with syndromic craniosynostosis and turribrachycephaly. This study provides an objective craniometric analysis to determine how PVDO affects anterior cranial morphology. METHODS: A retrospective chart review of patients who underwent PVDO was performed. Inclusion criteria included pre- and postoperative computed tomography (CT) scans within 3 months before surgery and another 1 to 6 months after device removal. Volumetric and craniometric data were derived using Mimics software and compared using paired t-test and Wilcoxon rank-sum test. RESULTS: About 65 patients underwent PVDO, and 13 patients met inclusion criteria. Mean age at intervention was 3.4 ± 4.2 years. Total cranial volume increased 249 ± 159 cm in all patients (P = 0.0001) and 380 ± 128 cm in patients younger than 1 year of age (n = 6, P =0 .0008). Supraorbital retrusion decreased from 5.44 ± 3.89 to 4.54 ± 3.91 mm postoperatively (P = 0.0004), decreasing significantly in patients without previous frontal surgery and not in those with previous frontal surgery (P = 0.2115; comparison P = 0.0047). Basofrontal angle decreased by 2.92 ± 2.16 degrees (P = 0.0004) with a greater decrease of 3.33±2.68 degrees in those younger than 12 months (P = 0.0289) and 2.58±1.74 degrees in those older (P = 0.0079). No change was found in anterior cranial height and anterofrontal angle (P > 0.05). CONCLUSION: PVDO improves frontal contour by decreasing supraorbital retrusion and reducing frontal bossing in syndromic craniosynostosis patients with turribrachycephaly. When combined with its demonstrated efficacy for cranial expansion, these frontal changes likely reinforce PVDO's ability to influence the timing of, and to a degree, the need for frontal surgery in this group.