Early Rigid Fixation Decreases Consolidation Period of Rigid External Distraction for Maxillary Hypoplasia in Cleft Patients Without Jeopardizing Surgical Outcome
Rigid external distraction is a promising treatment option in correcting maxillary hypoplasia in cleft lip and palate patients. But the cumbersome device and long consolidation period up to ten weeks demand great amount of patient compliance. Furthermore traumatic event may occur during the consolidation period that might injure the patient and affect the treatment outcome. Most importantly the maxillary segment may not be in the ideal position after distraction. Vertical distraction vector could be disturbed by masticatory force. Symmetry could also be unsatisfactory with accompanied occlusal plane canting. In effort to overcome these problems we have modified the treatment plan and applied rigid fixation to the maxilla after a reduced period of consolidation.
MATERIALS AND METHODS
Polley/RED system was applied for distraction osteogenesis in patients suffering maxillary hypoplasia due to cleft lip and palate. Before we have accumulated experience, we followed the manufacturer’s recommendation of 6 to 10 weeks of consolidation. Maxillary segment position was not ideal all the time. We started to reduce the consolidation period to three to four weeks and applied rigid fixation with delicate positional correction of the maxillary segment. A simultaneous bilateral sagittal split ramus osteotomy was performed to correct mandibular discrepancies and stabilize the occlusion.
Cephalometric analysis was performed in purpose to compare the relapse rate of the modified method with the relapse rate of the conventional method applied before we have started treatment plan modification. Relapse was measured after two years of follow up. The conventional method group contained five patients and the modified method contained eight patients.
METHODS OF DATA ANALYSIS
Relapse rate of each group was measured in terms of change in Sella-Nasion-A-point(SNA) degree and horizontal distraction amount. A line seven degrees clockwise from the Sella-Nasion line was considered the horizontal axis.
RESULTS
Mean change in SNA angle after distraction was 9.63 degrees for the conventional method group and 13.00 degrees for the modified method group. Mean distraction amount in horizontal direction was 10.5 mm for the conventional method group and 16.38 mm for the modified method group. Mean relapse of SNA angle was 3 degrees for the conventional method and 3.75 degrees for the modified group after two years. Mean relapse rate of SNA angle in the conventional group and modified group were 29.97 and 31.78 %, respectively. Mean relapse of horizontal distraction length was 3.625 mm for the conventional method and 3.875 mm for the modified method after two years. Mean relapse rate of horizontal distraction length in the conventional group and modified group were 33.85 and 23.84 %, respectively.
CONCLUSIONS
Based on our experience, we advocate that early application of rigid fixation may effectively reduce the time required for wearing rigid external distraction system in cleft lip and palate patients without compromising treatment outcome. Furthermore intervention before full consolidation provides the surgeon a chance to correct the maxillary segment into a more ideal position.
REFERENCES
- Seung-Hak Baek, Jin-Kyung Lee, Jong-Ho Lee, Myung-Jin Kim, and Jong-Ryoul Kim, Comparison of Treatment Outcome and Stability Between Distraction Osteogenesis and LeFort I Osteotomy in Cleft Patients With Maxillary Hypoplasia, Journal of Craniofacial Surgery. 2007; 18 (5): 1209-1215
- Kristian Andersen, Sven Erik Nørholt, Annelise Küseler, John Jensen, and Thomas Klit Pedersen, A Retrospective Study of Cleft lip and palate Patients' Satisfaction after Maxillary Distraction or Traditional Advancement of the Maxilla, Journal of Oral and Maxillofacial Research. 2012; 3(2): e3.