P48. Striking the Balance: Identifying Sagittal Advancement Thresholds in Cleft Orthognathic Surgery

PURPOSE: Orthognathic surgery is often required in patients with cleft palate (CP) to address midface hypoplasia and correct class III malocclusion. However, optimal maxillary advancement in relation to outcomes including relapse and velopharyngeal insufficiency (VPI) remains unclear. This study aims to identify predictors of relapse and VPI following orthognathic surgery. METHODS: A retrospective review of patients with CP who underwent orthognathic surgery between 2004-2024 was conducted. Patients with less than six months of follow-up were excluded. Primary outcomes were relapse, defined as recurrence of malocclusion requiring repeat orthognathic surgery, and VPI. Receiver operating characteristic curve analyses were performed. RESULTS: Overall, 110 patients met inclusion criteria. Mean age at surgery was 17.9 ± 2.2 years and the mean follow-up was 2.6 ± 1.8 years. Mean sagittal advancements were 6.9 ± 2.2 mm for Le Fort 1 advancement, and 16.3 ± 5.0 mm for distraction osteogenesis (p<0.001). The overall postoperative VPI rate was 22.7%, and the overall relapse rate was 14.5%. Patients with bilateral cleft lip and palate had higher relapse rates (p=0.015). Patients with advancement over 8.5mm were 5.5 times more likely to experience relapse (p=0.003), and patients with advancement over 7.5mm were 4.3 times more likely to experience VPI (p=0.002). BSSO reduced the risk of relapse by 3.8 times (p=0.023). CONCLUSION: Sagittal advancements under 7.5-8.5 mm reduced the risk of relapse and VPI following orthognathic surgery, while BSSO offered additional protection against relapse. These findings help to inform cleft-orthognathic surgical planning and preoperative counseling.