title: Endoscopically assisted anterior release and reduction through anterolateral retropharyngeal approach for fixed atlantoaxial dislocation.
abstract: METHODS
  A prospective study.
  
  
  OBJECTIVE
  To evaluate a novel technique involving an endoscopically assisted anterior release and reduction through an anterolateral retropharyngeal approach with minimum follow-up interval of 31 months.
  
  
  BACKGROUND
  Irreducible atlantoaxial dislocation is typically a chronic process that requires surgical treatment. However, the current literature does not agree on the single best method of treatment. Previously, the best outcomes have been reported with transoral reduction followed by anterior or posterior fixation. Despite recent innovations, numerous complications remain associated with this approach.
  
  
  METHODS
  About 21 consecutive irreducible atlantoaxial dislocation patients with mean age of 32 years underwent endoscopically assisted anterior release and reduction through the anterolateral retropharyngeal approach followed by posterior fixation. The primary pathologies included 8 late odontoid fractures, 7 cases of os odontoideum, 5 with laxity of the transverse ligament, and 1 with atlanto-occipital assimilation with a hypoplastic odontoid. Neurologic status was evaluated using the Japanese Orthopedic Association scoring system. Radiographic parameters including the atlantodental interval (ADI) and cervicomedullary angle were also measured. Follow-up data were obtained for a minimum of 31 months.
  
  
  RESULTS
  Anatomic reduction was achieved in 20 cases and near-anatomic reduction in 1 case. All patients had an uneventful recovery with significant improvement in neurologic function and radiographic parameters. No complications were seen. The atlantodental interval was corrected from an average 6.3 mm before surgery to 2.7 mm after surgery (P < 0.01). The cervicomedullary angle was also corrected from an average 109 degrees before surgery to 152 degrees after surgery (P < 0.01). Preoperative muscle strength was on average 3.5 (on scale from 1 to 5) and improved after surgery to 4.5 (P < 0.01). The average preoperative and postoperative Japanese Orthopedic Association scores were 9.6 and 15.5, respectively, indicating 82.8% improvement.
  
  
  CONCLUSIONS
  Endoscopically assisted anterior retropharyngeal release combined with posterior fixation is a safe and effective alternative for the treatment of irreducible atlantoaxial dislocation.
authors.affiliation: Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
authors.forename: Guohua
authors.initials: G
authors.lastname: Lü
authors.forename: Peter G
authors.initials: PG
authors.lastname: Passias
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Michal
authors.initials: M
authors.lastname: Kozanek
authors.forename: Lubos
authors.initials: L
authors.lastname: Rehak
authors.forename: Kirkham B
authors.initials: KB
authors.lastname: Wood
authors.forename: Guoan
authors.initials: G
authors.lastname: Li
authors.forename: Youwen
authors.initials: Y
authors.lastname: Deng
mesh_terms: D000293:Adolescent; D000328:Adult; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D019299:Decompression, Surgical; D004724:Endoscopy / Q000379:methods*; D005260:Female; D005593:Fracture Fixation, Internal; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000601:surgery*; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011859:Radiography; D016059:Range of Motion, Articular; D020127:Recovery of Function; D013123:Spinal Fusion / Q000379:methods*; D016896:Treatment Outcome