Optimising Fronto-Orbital Distraction for Management of Unicoronal Craniosynostosis

Unicoronal craniosynostosis (UCS) involves premature fusion of the left or right coronal suture, resulting in skull deformities and facial asymmetry. Fronto-orbital distraction (FOD) has proven effective for surgically correcting UCS; however, determining optimal surgical parameters (e.g. distraction angle, length, and distractor number) remains challenging. This study aimed to optimise FOD for UCS using finite element (FE) analysis and simulated surgical outcomes.

We developed a patient-specific FE model using pre- and postoperative computed tomography (CT) scans from a 23-day-old UCS patient. The model simulated FOD with varying distraction angles (20°, 30°, 40°), lengths (20-40 mm), and use of single or dual distractors. Thirty-six scenarios were analysed to evaluate impact on skull morphology, orbital symmetry, and facial correction. The model was validated against clinical outcomes using postoperative CT scans. Key metrics included orbital index symmetry and orbital dystopia angle (ODA).

Distraction length most significantly impacted outcomes, with 40-mm advancement yielding superior orbital symmetry. The optimal configuration (single distractor, 40°, 40-mm advancement) achieved an ODA of 2.2° and orbital index difference (OID) of 0.2%. Dual distractors offered only marginal improvements (ODA: 1.7°; OID: 0.2%) and introduced risks of excessive anterior displacement.

These findings suggest that optimal FOD outcomes for UCS can be achieved with a single distractor at 40° and 40-mm advancement. Dual distractors provided minimal additional benefit and may increase surgical complexity and risks. The validated FE model offers a quantitative framework for surgical planning and improving the precision of craniosynostosis correction.