A Quantification of Scalp Thickness before and after Posterior Vault Distraction Osteogenesis.

SUMMARY: Previous literature has documented craniometric changes of the bony calvaria, increases in intracranial volume, and resolution of Chiari malformations following posterior vault distraction osteogenesis. No studies have analyzed changes to the soft-tissue envelope after posterior vault distraction osteogenesis. In this study, the authors aimed to provide objective measurements of scalp thickness in patients undergoing posterior vault distraction osteogenesis, utilizing facial soft-tissue thickness as a proxy to control for growth. The authors hypothesized that the soft tissues of the scalp are not made thinner by the distraction process, either in the region of distraction or in neighboring areas. Subjects who underwent posterior vault distraction osteogenesis for a craniosynostosis diagnosis who had high-resolution predistraction and post-distractor removal computed tomographic scans within 100 days of each operation were included. The scans were analyzed on Materialise Mimics version 21 software (Materialise, Ghent, Belgium). Six key craniometric landmarks (glabella, pogonion, zygion, vertex, euryon, and opisthocranium) were identified on the three-dimensional bone masks in the Frankfort horizontal plane. The points were overlaid onto soft-tissue thickness masks and thicknesses were recorded. Percent change in postoperative facial soft-tissue thickness was used to control for growth of the craniofacial soft-tissue envelope during the study interval. The preoperative and postoperative posterior vault distraction osteogenesis cohorts did not differ significantly at the glabella, pogonion, opisthocranium, vertex, and zygion. The corrected median thickness at the euryon was significantly increased in the post-posterior vault distraction osteogenesis cohort [2.67 mm (IQR, 2.49 mm to 4.02 mm) versus 5.26 mm (IQR, 3.83 mm to 7.82 mm), p = 0.002]. This is the first study to quantify changes in soft-tissue thicknesses preoperatively and postoperatively in patients undergoing posterior vault distraction osteogenesis, demonstrating maintenance of scalp thickness. .

CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.