Comparative 3-Dimensional Analysis of Pi Versus Posterior Vault Remodeling for Nonsyndromic Single-Suture Sagittal Craniosynostosis Correction

Purpose: The Pi procedure and posterior vault reconstruction (PVR) address sagittal craniosynostosis by increasing intracranial volume through different surgical techniques. This study aims to compare the volumetric and cranial shape outcomes between these procedures. Methods: A 3D analysis of pre- and postoperative CT scans from 18 patients with nonsyndromic sagittal craniosynostosis treated at a single institution (2018–2023) was performed using SyngoVia. Patients were categorized by operative technique, with PVR patients further stratified by those requiring bifrontal orbital advancement reconstruction (BFOAR). Cranial index (CI) and intracranial volumes were compared with age- and sex-matched controls using paired and unpaired t tests. Results: Ten patients underwent the Pi procedure, and 8 underwent PVR. The Pi procedure increased mean CI from 70.2 to 77.0 ( P =0.010), though CI remained significantly lower than controls ( P =0.007). Posterior vault reconstruction did not significantly change CI, even in those requiring BFOAR, with postoperative CI remaining lower than controls ( P =0.002). Preoperatively, both groups had significantly larger intracranial volumes than controls ( P =0.043, P =0.042). Postoperatively, Pi patients maintained significantly larger intracranial volumes ( P =0.002), while PVR and PVR+BFOAR patients’ volumes normalized to controls. In addition, regional volumetric differences between the 2 groups suggest differing distributions of cranial expansion. Conclusions: Neither procedure fully corrected CI. Posterior vault reconstruction normalized intracranial volume due to an initially elevated preoperative volume, whereas the Pi procedure significantly increased it. These findings highlight differences in postoperative cranial morphology and suggest further studies are needed to determine the long-term functional and aesthetic implications.