Poster 05: Maxillary Distraction Osteogenesis in Cleft Patients

Poster Session photopolymer jigs with drill holes were fabricated to ensure precise distractor placement intraoperatively. Inverted L-osteotomies were used in both cases because we were able to preoperatively ascertain that there would be adequate proximal bony structure for distractor placement. This minimized the risk of injuring developing tooth buds and the inferior alveolar nerve associated with an oblique osteotomy. The vector direction was manipulated and individualized for the patient’s mandibular characteristics. CAS also enabled us to determine that linear distractors were sufficient to achieve our goals without producing anterior open bites. Finally, we were able to determine the required length of distraction in each case. This allowed us to preserve bony structure by placing the smallest distractor possible to produce the desired outcome. KLS micro-Zurich distractors were used in both cases. Methods of Data Analysis: The pre- and post-distraction lateral cephalometric radiographs and cephalometric parameters were compared to evaluate distraction outcome. In addition, the computer simulated distraction cephalometric tracing was compared with the actual post-distraction cephalometric tracing to determine the predictability of the CAS in DO. Results: Postoperative evaluation revealed a dramatic increase in the PAS and SNB angle when overlaying the pre- and post-distraction lateral cephalometric radiographs. A decrease in the ANB angle demonstrated improvement in the maxillo-mandibular relationship. Comparison of the computer-simulated distraction outcome and the actual post-distraction outcome revealed no significant differences in our small series. At surgery the jigs were easy to use and allowed precise placement of the small distractors in very hypoplastic mandibles. Conclusion: Cephalometric evaluation highlights the accuracy and predictability of CAS in DO. We believe computer simulated DO is an excellent tool with obvious advantages in predicting the osteotomy type and location, vector of distraction, distraction device, and length of distraction. CAS technology is especially useful in the neonate because the importance of precisely predicting these factors correctly is amplified by the miniature size of the neonatal mandible; there is simply very little room for error. It is likely that the accuracy and predictability of CAS is such that it has the potential to become a fundamental component of neonatal DO. Acknowledgements: We thank Andy Battan and Katie Weimer at Medical Modeling for their help with these cases.

POSTER 05 Maxillary Distraction Osteogenesis in Cleft Patients L. Jones: University of Alabama at Birmingham, P. D. Waite Patients with repaired cleft palates often exhibit severe maxillary deficiencies that are difficult to treat with traditional Le fort I advancements due to scar tissue that hinders large advancements. This study involves 32 cleft (unilateral and bilateral) patients over a 7-year period that were treated with rigid external distraction devices with Le fort I osteotomies. A high Le fort I osteotomy was performed followed by a latency period, active distraction period, and consolidation period of approximately 3 times the active distraction period. Lateral cephalometric radiographs were obtained prior to surgery, after the active phase and at follow up appointments after the consolidation phase. For the purposes of our study, these cephalometric radiographs were all digitized. Angular as well as linear measurements were then analyzed. These measurements at the various periods were then analyzed using paired t test to assess the movements gained after the active phase as well as the long-term stability following consolidation. Measurements obtained for analysis included SNA and ANB angles as well as maxillary points A, ANS, and PNS at each of the above stages. The average age of patients treated was 11.7 years, and the average time frames for various stages were as follows: latent period of 6.2 days, average active phase of 11 days and average consolidation stage of 32 days. Average long-term follow up is 26 months. The results of this investigation reveal significant changes in both angular and horizontal measurements of the maxilla. This further solidifies use of rigid external distraction for the treatment of maxillary deficiency in cleft patients. The advantages of this treatment modality include earlier surgical intervention without placement of internal hardware, and early improvement of facial form to help avoid social stigma. This study contributes to the smaller sample studies that have found similar results.1,2 Additional long-term follow-up of this patient population is warranted for further long-term stability analysis as they continue to grow and develop. References:

References: Edwards. Computer-assisted craniomaxillofacial surgery. Oral & Maxillofacial Surgery Clinics of North America. Vol.22, Issue 2, Pages 117-134. Troulis, Kaban. Complications of mandibular distraction osteogenesis. Oral & Maxillofacial Surgery Clinics of North America. Vol.15, Issue 2, Pages 251-264.

e-42

Gu ¨ rsoy S, Hukki J, Hurmerinta K: Five year follow-up of maxillary distraction osteogenesis on the dentofacial structures of children with cleft lip and palate. J Oral Maxillofac Surg. 68(4):744-50, 2010. Figuroa A, Polley J, Friede H, Ko E: Long term skeletal stability after maxillary advancement with distraction osteogenesis using a rigid external distraction device in cleft maxillary deformities. Plast Reconstr Surg 114: 1382-92, 2004.

AAOMS • 2012