title: Reliabilities of and correlations among five standard methods of assessing the sagittal alignment of the cervical spine.
abstract: METHODS
  The reliabilities of and correlations among 5 standard methods of assessing cervical sagittal alignment were evaluated.
  
  
  OBJECTIVE
  To investigate the reliabilities of and correlations among 5 standard methods of assessing cervical sagittal alignment.
  
  
  BACKGROUND
  Although various cervical sagittal alignment assessment methods are widely used, their relative reliability and intercorrelation have not been reported.
  
  
  METHODS
  From 442 lateral cervical radiographs, 40 with lordotic, 40 with straight or sigmoid, and 40 with kyphotic alignment were selected. Two orthopedic surgeons independently evaluated the sagittal alignment in each group twice using CCL, C1-C7 Cobb, C2-C7 Cobb, sagittal tangent, and the Ishihara methods. Intraobserver and interobserver reliabilities were confirmed and the correlations among the 5 methods were measured.
  
  
  RESULTS
  Intraobserver and interobserver reliabilities for all 5 methods were good. In the lordotic group, the correlations among all 5 methods were consistently strong (r = 0.731 to 0.922). In the straight or sigmoid group, the correlations were weak to moderate among the CCL, C2-C7 Cobb, sagittal tangent, and Ishihara methods but tended to be weak between these 4 methods and the C1-C7 Cobb method (r = -0.245 to 0.777). In the kyphotic group, the correlations were also weak to moderate among the same 4 methods, and were statistically insignificant between them and the C1-C7 Cobb.
  
  
  CONCLUSIONS
  The correlations among the CCL, C1-C7 Cobb, C2-C7 Cobb, sagittal tangent, and Ishihara methods are strong when lordosis is retained; otherwise, they are moderate to poor. In the kyphotic group, C1-C7 Cobb has no significant correlation with the other 4 methods.
authors.affiliation: Department of Orthopaedic Surgery, Matsunami General Hospital, Gifu, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Ohara
authors.forename: Kei
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Naganawa
authors.forename: Kazu
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Katsuji
authors.initials: K
authors.lastname: Shimizu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008141:Lordosis / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012107:Research Design / Q000592:standards*