A Three-Dimensional-Based Morphometric Analysis of a Standardized Overcorrection Technique for Fronto-Orbital Advancement in Metopic Craniosynostosis

Abstract

Introduction

The concept of “overcorrection” for trigonocephaly has been reported to achieve both anterior cranial fossa expansion and normalization of craniofacial form. The purpose of this study is to describe in detail a standardized technique to fronto-orbital advancement utilizing the concept of “overcorrection” and objectively evaluate intermediate results.

Methods

This retrospective study included patients with isolated metopic synostosis who underwent surgery via the proposed surgical technique and age and sex-matched unaffected controls. Craniofacial morphometric analysis was performed on pre-, immediate post-, and intermediate postoperative (>2 years) three-dimensional (3D)-rendered computed tomographic (CT) scans and photographs. Key CT-based measurements included interzygomaticofrontal suture distance (IZFS), endocranial bifrontal angle (ECA), and temporal expansion. 3D photogrammetry was performed using established measurements and associated Z-scores converted. A Paired t-test and analysis of variance were performed when appropriate.

Results

Forty-one patients were included. A comparison of pre- and immediate postoperative CT scans demonstrated statistically significant increases in all measurements. Subset analysis of 12 patients with intermediate follow-up (age: 39.6 ± 3.6 months) demonstrated significant differences from preoperative values except for IZFS, which decreased from immediate postoperative values and was smaller than age- and sex-matched controls. 3D photogrammetry demonstrated a mean Z-score above the norm for frontal breath. 3D photogrammetry is also positively correlated with CT-based measurements.

Conclusions

This standardized “overcorrection” approach for trigonocephaly can provide the appropriate changes to maintain a normal ECA despite a reduction in bifrontal width over time. 3D photogrammetry positively correlated with CT-based measurements and may provide useful information when following patients clinically. Long-term follow-up assessment to determine the necessary degree of overcorrection at skeletal mature is needed.