“Long-term Outcomes of Regional Morphology in Spring-Assisted Surgery and Cranial Vault Remodeling”

Abstract

Spring-assisted surgery (SAS) and cranial vault remodeling (CVR) are widely used surgical techniques for correction of sagittal craniosynostosis (SC). This study evaluates changes in regional morphology of SC patients who have undergone SAS or CVR using the frontal bossing index (FBI), occipital bulleting index (OBI), vertex narrowing index (VNI), and scaphocephalic severity index (SCI) to capture differences in anterior protrusion, posterior protrusion, width restriction, and global dysmorphology, respectively. Indices were measured on CT and 3D photographs (n=788) of 257 SC patients from 2001-2022 who underwent SAS (n=177) and CVR (n=80). Short-term and long-term outcomes were evaluated. Mean age at time of surgery was older in the CVR cohort (mean 22.55±16.00) than in the SAS cohort (mean 4.56±2.24; p<0.05). Pre-operatively, the SAS cohort had more severe regional dysmorphology in FBI, VNI, and SCI (p<0.05) relative to the CVR cohort. Frontal bossing consistently improved over time in both cohorts. Head width had improvement as soon as 0-6 months postoperative (p<0.05); however, it consistently regressed after the initial improvement in both cohorts. Global head shape initially improved in the CVR cohort, but over time regressed. In contrast, SAS maintained improvements in SCI over time with significantly better percent change in every age interval (p<0.05). The FBI, OBI, VNI, and SCI are useful tools for monitoring head shape and growth. SAS and CVR achieve similar morphologic outcomes despite more severe pre-operative morphology in the SAS group. Trending index changes with growth among the two cohorts suggests improved longevity of correction in the SAS group.