title: Three-dimensional morphology and kinematics of the craniovertebral junction in rheumatoid arthritis.
abstract: METHODS
  A case-series study.
  
  
  OBJECTIVE
  To measure the 3-dimensional (3D) morphology and kinematics of the craniovertebral junction (CVJ) using a 3D computed tomography (CT) model; to reveal abnormal patterns and the relationships between pathology and kinematics.
  
  
  BACKGROUND
  Evaluations using radiography, 2-dimensional (2D) CT and magnetic resonance imaging have limitations because of the complex 3D structure of the CVJ.
  
  
  METHODS
  Twenty-four rheumatoid arthritis patients (21 females, 3 males) with cervical involvement underwent CT scanning of the cervical spine from the basilar process of the occipital bone to the first thoracic vertebra in neutral and flexed positions. The 3D morphology of the occipital condyle, atlas, and axis were classified based on the type of deformity observed. Periodontoid lesions (continuous bony lesions between the atlas and the odontoid process) were also noted. The 3D kinematics in the atlanto-occipital and atlantoaxial joints were evaluated using the volume merge method.
  
  
  RESULTS
  Deformities in the atlanto-occipital joints appeared more frequently than those in the atlantoaxial joints. The most common instability pattern was flexural rotation during flexion at the CVJ. The direction of translational motions during flexion was posterior in the atlanto-occipital joint and anterior and caudal in the atlantoaxial joint.
  
  
  CONCLUSIONS
  The results suggest that bilateral occipital condyle deformation, unilateral and bilateral mass collapse, and periodontoid lesions may affect flexion/extension rotational instability in the atlantoaxial joint. In addition, unilateral occipital condyle deformation and atlantoaxial joint stability may affect sagittal translational instability to the posterior side in the atlanto-occipital joint. The noninvasive 3D CT imaging technique employed here would be useful for predicting the prognosis of patients with rheumatoid deformities at the CVJ.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, Japan. r-taka@koto.kpu-m.ac.jp
authors.forename: Ryota
authors.initials: R
authors.lastname: Takatori
authors.forename: Daisaku
authors.initials: D
authors.lastname: Tokunaga
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Hase
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Mikami
authors.forename: Takumi
authors.initials: T
authors.lastname: Ikeda
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Harada
authors.forename: Kan
authors.initials: K
authors.lastname: Imai
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Ito
authors.forename: Tsunehiko
authors.initials: T
authors.lastname: Nishimura
authors.forename: Howard S
authors.initials: HS
authors.lastname: An
authors.forename: Nozomu
authors.initials: N
authors.lastname: Inoue
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D001696:Biomechanical Phenomena / Q000502:physiology; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*