"Anterior skull base and pericranial flap ossification after frontofacial monobloc advancement".

Background: Frontofacial monobloc advancement (FFMBA) creates a communication between the anterior cranial fossa and nasal cavities. To tackle this issue, trans-orbital pericranial pedicled flaps (PF) are routinely performed in our center. This study aimed to assess the post-operative ossification of the anterior skull base and PF following FFMBA, and to identify factors influencing this ossification. Methods: Measurements of the skull base only (SB) and of the ossified PF together with the SB (SB-OPF) were performed on CT scans at the naso-frontal (NF) and the naso-ethmoido-frontal (NEF) junctions. The total thickness of the skull vault was measured and a qualitative defect score for the anterior skull base was computed. Results: Twenty-two patients who underwent FFMBA at a median age of 3.1 years (1.9 - 3.6) were included: 14 with Crouzon (CS), 5 with Pfeiffer (PS) and 3 with Apert syndrome (AS). One year and five years after surgery, the distraction gap was completely ossified in the anterior skull base midline in all patients. SB-OPF was thicker in patients than in controls at these two time points (p