SO13. Long-term Morphometric and Functional Outcomes of Frontofacial Advancement in Syndromic Craniosynostosis

PURPOSE: Midface surgery increases airway volumes, but little is known about how various surgical techniques affect the upper airway in the short- and long-term. The present study addresses this gap by analyzing longitudinal volumetric, craniometric, and functional outcomes following LeFort III (LFIII), monobloc, and monobloc with LeFort II (LFII) procedures for midface hypoplasia in syndromic craniosynostosis. METHODS: Patients with syndromic craniosynostosis who underwent midface surgery were included. Three-dimensional reconstructions of the pre- and postoperative nasopharyngeal airways were generated using Materialize Mimics. Surgical technique, airway changes, anterior facial movement, polysomnography data, and demographics were analyzed. RESULTS: Forty-one patients who underwent 45 procedures were included, 24 LFIII, 18 monoblocs, and 3 monoblocs with LFII. Nasopharyngeal airway volume increased post-operatively by 111.0% (interquartile range: 36.2-172.5) across all cohorts with both nasal and pharyngeal airway increasing on early (<12 months) and late (>12 months) follow-up (p<0.05). All midface surgical techniques increased airway volumes similarly (p>0.05). The midface was advanced on early post-operative imaging (anterior nasal spine-porion midpoint length: 72 (66-77) mm vs. 91 (85-95) mm), with some relapse (85 (80-99) mm) on later imaging. The airway expanded 545 (368-902) mm3 for each mm of sagittal advancement. Both OAHI and SpO2 nadir improved after surgery (p<0.05). CONCLUSION: Nasopharyngeal airway volume increases in the short and long-term following LeFort III, monobloc, and monobloc with LeFort II procedures, even as the midface experiences some long-term sagittal relapse. Each mm of sagittal midfacial movement results in 545 mm3 of airway volumetric increase regardless of osteotomy choice.