Quantitative intraoperative assessment of fronto-orbital advancement and remodelling in craniosynostosis

Intraoperative morphometric analysis provides immediate feedback for evaluating surgical outcomes in infants with craniosynostosis undergoing fronto-orbital advancement and remodelling. However, current intraoperative assessment primarily relies on surgeon's judgement and clinical experience. This study aimed to develop a computational method for comprehensive analysis of detailed morphological features in the intraoperative 3D surface scan acquired with a structured-light handheld scanner.

Our method consists of three stages: First, we computed cephalometric measurements, such as interfrontal angle (IFA) and cranial index (CI). Second, we developed a coarse-to-fine registration method to align the pre- and intraoperative surfaces, enabling accurate superimposition of non-operated region. Finally, we employed geometric morphometrics to examine frontal morphological shape differences. The proposed method was applied to one patient with trigonocephaly and one with Saethre-Chotzen syndrome (SCS).

A small root mean square error (0.5-0.6 mm) indicated high registration accuracy. The cephalometric measurements and colour maps of intraoperative geometric changes indicated frontal advancement in both the anterior and lateral directions, with an increased IFA in the trigonocephaly case and a decreased CI in the SCS case. Geometric morphometric analysis suggested that the central forehead remained relatively flat on the intraoperative 3D surface, although the overall frontal morphology approached that of the control group.

The proposed analytical method combined with 3D scanning provides new insights into quantitative intraoperative assessment through the comparison of cephalometric measurements, quantification of geometric surface changes, and examination of morphological variation. This framework has the potential to be integrated into routine surgical workflows for craniosynostosis treatment.