S4B-25 SESSION 4B: ORTHOGNATHIC / TREACHER-COLLINS MINIMAL DISRUPTION DISTRACTION IN SEVERE MANDIBULOFACIAL DYSOSTOSIS

Abstract

Introduction: Severe Nager and Treacher Collins (TCS) patients frequently fail conventional distraction techniques. Degloving for osteotomy access and hardware retrieval delays bony healing and affects relapse. Further, high distraction forces in mandible-borne distractors may result in hardware failure, TMJ injury, or poor patient tolerance. To counter this, we designed a minimal access approach with transconjunctival high LeFort through reconstructed orbital floors combined with minimal dissection BSSO. Custom, non-buried anchorage devices permit aggressive, halo-borne counterclockwise traction. This approach has optimized airway outcomes and dramatically improved stable correction in our cohort. Methods: A total of 21 severe TCS or Nager patients underwent Lefort III/BSSO distraction osteogenesis were examined. 13 had prior MDO operation and 9 had a tracheostomy. Prior to Lefort III, malar and periorbital augmentation were performed using BMP2-soaked particulate allograft bone. This was performed serially (mean 2.7). Minimal dissection transconjunctival Lefort III and BSSO were then performed. Custom non-buried locking plates are designed to permit fixation between tooth roots. The maxillary plate is 1 piece to stabilize the hemimaxillas. The mandible plate is passed through a transmental tunnel to provide joystick-control of the distraction fragment. These are asymmetrically distracted from a RED device, the maxilla is consolidated once adequate counterclockwise advancement is achieved. The mandible is overdistracted to permit airway clearance and a consolidation period and/or intermaxillary fixation following distraction. Results: The number of distraction correlated with severity of midfacial deformity. In contrast, degree of micrognathia in infants and young children was not correlated with need for repeat distraction. Early mandibular distraction avoided secondary maxillary changes and was also associated with minimal loss of mandibular correction. Significant midface soft tissue advancement often required subsequent canthoplasty (14), midface bony contouring (10) or nasal dorsum augmentation with rib graft (4). 5 patients required a later bimaxillary advancement. Of the patients with tracheostomy 3/5 are decannulated and another two are eligible but prefer to finish ear reconstruction prior to decannulation. Conclusion: By combining minimal access techniques and custom hardware, we avoid soft tissue degloving and achieve enhanced outcomes in severe Treacher Collins and Nager syndrome. This regimen permits aggressive counterclockwise movement, more completely correcting both upper airway obstruction and facial aesthetics in patients with severe mandibulofacial dysostosis.