title: Myelopathy resulting from the atlantodental hypertrophic osteoarthritis accompanying the dens hypertrophy. Two case reports.
abstract: METHODS
  This is a report of two patients who sustained cervical myelopathy that seemed to be associated with hypertrophic atlantodental osteoarthritis accompanying dens hypertrophy.
  
  
  OBJECTIVE
  Pathogenesis of hypertrophic osteoarthritis in the atlantodental articulation was elucidated, and these two patients were treated by C1 decompressive laminectomy with or without posterior fusion.
  
  
  BACKGROUND
  One case of myelopathy resulting from the hypertrophic nonunion of the dens has been reported, but to the authors' knowledge, there have been no reports describing a case similar to those presented in this report.
  
  
  METHODS
  History, physical findings, and image examination findings common to the two cases were analyzed to elucidate pathogenesis of hypertrophic osteoarthritis in the atlantodental articulation. C1 decompressive laminectomy alone was performed in one patient and additional atlantoaxial transarticular fixation in the other patient.
  
  
  RESULTS
  Myelopathy in two patients was caused by the cervical cord compressed between the hypertrophic and sclerotic dens and the anteriorly displaced posterior arch of the atlas in the developmentally small atlas ring. Postoperative neurologic recovery was satisfactory with the atlantoaxial solid fusion.
  
  
  CONCLUSIONS
  The atlantodental hypertrophic osteoarthritis accompanying the dens hypertrophy seemed to have developed because of post-traumatic atlantoaxial instability. Their developmentally small atlas ring may be a predisposing factor toward the development of myelopathy.
authors.affiliation: Department of Orthopedic Surgery, Akita University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sato
authors.forename: S
authors.initials: S
authors.lastname: Senma
authors.forename: E
authors.initials: E
authors.lastname: Abe
authors.forename: H
authors.initials: H
authors.lastname: Saito
authors.forename: H
authors.initials: H
authors.lastname: Saito
mesh_terms: D000368:Aged; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D006984:Hypertrophy / Q000150:complications; D004204:Joint Dislocations / Q000473:pathology; D007593:Joint Instability / Q000150:complications / Q000503:physiopathology; D007796:Laminectomy / Q000379:methods; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009809:Odontoid Process / Q000293:injuries / Q000473:pathology*; D010003:Osteoarthritis / Q000150:complications* / Q000503:physiopathology; D011859:Radiography; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology / Q000601:surgery; D013123:Spinal Fusion