title: Nonunion of the external maxillary distraction in cleft lip and palate: analysis of possible reasons.
abstract: OBJECTIVE
  Distraction osteogenesis (DO) is an effective way to treat severe maxillary deficiency in patients with cleft lip and palate. It has been reported to have long-term stability and low relapse rate compared with conventional maxillary osteotomy in large maxillary movement. However, complications such as nonunion are seldom reported. While developing our external distraction techniques, we had 4 nonunion cleft lip and palate (CLP) patients. The aim of this study is to analyze the possible reasons for these conditions by comparing them to patients successfully treated at 1 craniofacial institute.
  
  
  METHODS
  Fifty-six patients with CLP deformities treated with external maxillary distraction from 2000 to 2006 in 1 craniofacial center were reviewed. Among them, 17 had full records and follow-up time of more than 1 year. They had rigid external halo distraction with dental splint after a high Le Fort I osteotomy. Distraction was started at 5 days with a rate of 1 mm per day until the maxilla acquired the planned correction. Consolidation time ranged from 4 weeks to 3 months. Patients' general information, DO protocol, and cephalometric radiograph measurements before DO, immediately after DO, and follow-ups were evaluated.
  
  
  RESULTS
  Thirteen of 17 patients successfully completed DO, whereas 4 others developed dental occlusion relapse 2 to 3 months after device removal. Later jaw surgery showed nonunion at the distraction sites. These were our first patients treated with external distraction. Their consolidation time was from 4 to 6 weeks with a mean of 5.2 weeks. After increasing the consolidation time up to 12 weeks, all of the other 13 patients had successful results without nonunion. Their mean consolidation time was 9.8 weeks. The nonunion group had significantly shorter consolidation time, older age, and larger distraction osteogenesis (DO) advancement than the successful group statistically. There was also a greater percentage of bilateral CLP patients in the nonunion group than in the successful treatment group. Among the 4 nonunion patients, 2 had failed alveolar bone graft before DO, and 3 did not have face mask retention therapy after device removal. The horizontal relapse rate in the 13 successful patients was 1 to 3 mm (mean, 11.9%) after 1 to 3 years of follow-up. All of these patients had good occlusion in the short-term follow-up (1 yr). Five developed end-to-end or Class III malocclusion in the long-term follow-up (1-3 yrs) because of maxillary relapse and continued mandibular growth that required jaw surgery later.
  
  
  CONCLUSIONS
  A short consolidation time can cause nonunion, and should be lengthened to 12 weeks or more for a stable maxilla. Older age, bilateral CLP, large DO advancement (>15 mm), and compromised bone healing are the risk factors for nonunion.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Shanghai Ninth People's Hospital, Affiliated with Shanghai Jiao Tong University, School of Medicine, Shanghai, PR China.
authors.forename: Dongmei
authors.initials: D
authors.lastname: He
authors.forename: David G
authors.initials: DG
authors.lastname: Genecov
authors.forename: Raul
authors.initials: R
authors.lastname: Barcelo
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002508:Cephalometry; D002648:Child; D002675:Child, Preschool; D002971:Cleft Lip / Q000150:complications; D002972:Cleft Palate / Q000150:complications* / Q000473:pathology / Q000601:surgery; D016267:External Fixators; D005260:Female; D006801:Humans; D008297:Male; D008313:Malocclusion, Angle Class III / Q000209:etiology; D008437:Maxilla / Q000601:surgery*; D008844:Micrognathism / Q000209:etiology / Q000601:surgery; D056948:Orthognathic Surgical Procedures / Q000009:adverse effects* / Q000379:methods*; D019857:Osteogenesis, Distraction / Q000009:adverse effects* / Q000295:instrumentation; D019340:Osteotomy, Le Fort; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D017211:Treatment Failure