Postsurgical changes in osseous dysmorphology of the midface and mandible in unilateral coronal craniosynostosis

Background: Early management of unilateral coronal synostosis (UCS) aims to treat the cranial abnormality with the hope of improving middle and lower facial morphology. This study analyzed osseous volume and 3-dimensional distances in the midface and mandible of patients with UCS to assess changes in facial symmetry following a cranial vault procedure. Methods: Patients who underwent fronto-orbital advancement for UCS repair between 1981 and 2012 with follow-up of at least 3 years were included. Computed tomography-based 3-dimensional reconstructions of the mandible and LeFort III midface were divided by 3 midline osseous landmarks and measured for volume. Distances between 11 osseous landmarks were measured in the midface and mandible. Ratios between the measurements on synostotic and nonsynostotic sides were calculated. Presurgical to postsurgical changes were evaluated with paired samples t tests. The study was powered to detect differences between preoperative and postoperative ratios of at least 3%. Results: Eleven patients were included. Mean age at initial imaging was 4.7 ± 3.2 months (range, 0.4 - 9.2 months) with postoperative follow-up of 9.0 ± 5.3 years (range, 3.3 - 17.0 years). Midfacial symmetry of osseous volume improved following surgery (synostotic to nonsynostotic ratio, 94.1% vs 98.9%, P = 0.044). The width (P < 0.001), height (P = 0.039), and anterior - posterior depth of the midface (P = 0.011) also became more symmetric. In the mandible, however, volumetric and linear symmetry did not improve. Conclusions: Symmetry of the midface, but not the mandible, improves significantly following the cranial procedure in patients with UCS.