Does the Rigid External Distraction Device Alter Maxillary Pitch in Cleft Maxillary Distraction?

Objective: The rigid external distraction (RED) device is reported to have the ability to three-dimensionally reposition the maxilla. The purpose of this study is to assess the ability of RED to intentionally alter the maxillary pitch. Design: Retrospective cohort study. Setting: Institutional practice. Patients: A retrospective chart review was completed over the past 12 years and a total of 50 patients met the inclusion criteria. Main outcome measures: Cephalometric changes and alteration in palatal plane angle. Methods: Cephalometric analysis of standardized landmarks was completed on calibrated, standardized lateral cephalograms. Pre-distraction and post-consolidation variables were compared via a two-tailed paired t-test. Results: The mean age at surgery of 12.2 +/- 3.2 years. Through distraction osteogenesis (DO), the maxilla was moved anteriorly with a mean distraction distance of 8.4 +/- 4.8 mm. The mean change in the angles sella-nasion-A-point angle (SNA), sella-nasion-B-point angle (SNB), and A-point-nasion-B-point angle (ANB) were 10.2 +/- 4.8, 0.9 +/- 2.7, and 9.3 +/- 4.1, respectively. The mean change in the palatal plane angle was -4.4 +/- 3.7. The mean change in the vertical position of the anterior nasal spine (ANS) and posterior nasal spine (PNS) in relation to the Frankfort horizontal (FH) were -2.0 +/- 4.1 mm and 1.7 +/- 3.8 mm, respectively. Conclusion: This study documents short-term findings of RED in a large cleft lip and palate (CLP) population. Despite positioning of distraction eyelets superior to the theoretical center of resistance, a counterclockwise (CCW) rotation of the palatal plane occurred. This suggests that adjunctive methods of vector control should be considered if clockwise (CW) rotation of the palatal plane is intended with the RED device.