S12-12 SESSION 12: FACIOCRANIOSYNOSTOSIS – PART II MONOBLOC MINUS LEFORT II: THE ROLE OF DIFFERENTIAL DISTRACTION FOR TREATMENT OF THE APERTS CRANIOFACIAL PHENOTYPE

Abstract

Introduction: Apert patients often require differential advancement of the forehead, orbits, and midface to correct fronto-orbital retrusion, lengthen the midface and nose, and close the anterior open bite. While traditionally done in stages, the Monobloc + Le Fort II distraction addresses these differential movements in a single operation. Advancement of the forehead and midface is accomplished with the monobloc, while the nose and central midface is inferiorly advanced and rotated using the Le Fort II distraction. The purpose of this study is to evaluate the skeletal 3D cephalometric changes utilizing this technique in the management of Aperts syndrome. Methods: A retrospective review was performed of the senior surgeons experience utilizing this technique in patients with Aperts syndrome. Pre and post distraction 3D CT cephalometrics were analyzed and compared to a historical published cohort of Aperts patients. Vertical and axial facial ratios were calculated before and after distraction, and these ratios were also compared between cohorts. Results: 3 patients with Aperts syndrome underwent a Monobloc + lefort II differential distraction at an average age of 8 years, and with an average length of follow up of 30 months. The following 3D cephalometric landmarks and angles were measured: Glabella, nasion, incisor midline, ANS, sella, lateral inferior orbit, SNA, SNB, occlusal plane, and maxillary mandibular incisor relationship (see chart). Average Vertical Facial Movements ANS to N: 16.3mm N to Lateral inferior orbit (LIO): 3.81mm; Average Axial Facial Movements and Ratios ANS to Sella: 31.1mm Sella to LIO: 9.05mm Sella to LIO/S to ANS: 0.290 Comparison to historical control in the literature: Lefort II distraction with zygomatic repositioning. Axial facial movement ratio: Sella to LIO/S to ANS Monobloc/Lefort II mean: 0.292 Lefort II/Zygoma Repositioning: 0.276 P = 0.43 (NS) Vertical Facial Movements Ratio: N to LIO/N to ANS Monobloc/Lefort II: 0.241 Lefort II/Zygoma Repositioning: 0.203 Conclusion: Differential distraction with the Monobloc + Lefort II allows for resolution of exorbitism, improvement in negative canthal tilt, lengthening of the nose, and closure of the anterior open bite in patients with Apert syndrome. The increased distraction and rotation of the central midface results in more normal facial ratios that are not observed with traditional monobloc distraction.