title: Centroid method: reliable method to determine the coronal curvature of scoliosis: a case control study comparing with the Cobb method.
abstract: METHODS
  Observational study with three examiners.
  
  
  OBJECTIVE
  To compare the reliability of the Cobb and centroid methods.
  
  
  BACKGROUND
  The Cobb method is considered to be the gold standard in scoliosis measurement despite its low reliability. In adolescent idiopathic scoliosis (AIS) patients, the centroid method can be a good method for measuring scoliosis.
  
  
  METHODS
  Sixty whole spine postero-anterior radiographs were collected to compare the reliability of the Cobb and centroid methods in AIS patients. Sixty radiographs were measured twice by each of the three examiners using the two measurement methods. The data were analyzed statistically to determine the inter- and intraobserver reliability.
  
  
  RESULTS
  In comparisons of inter- and intraobserver reliability of all 60 radiographs, the inter- and intraclass coefficients (ICCs) were higher in the centroid (>0.969) than in the Cobb method (>0.832), although both were in the excellent range. The mean absolute difference (MAD) values were higher in the Cobb method (<7.15° vs. <3.75°), and >5° in five comparisons. Regarding measures of mismatched radiograms, the inter- and intraobserver MAD values were higher in the Cobb method (<9.81° vs. <3.82°), and >5° in six comparisons. And, the ICCs were higher in the centroid method (>0.972) than the Cobb method (>0.758). In immature radiograms, the ICCs were higher in the centroid (>0.973) than in the Cobb method (>0.764), even though it was in the excellent range. And, the inter- and intraobserver MAD values were higher in the Cobb method (<8.49° vs. <3.99°), and >5° in seven comparisons.
  
  
  CONCLUSIONS
  The centroid method is more reliable for measuring scoliosis in AIS than the Cobb method, and it can substitute the Cobb method, which showed high variability.
authors.affiliation: Department of Orthopedics, Scoliosis Research Institute, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Jae-Young
authors.initials: JY
authors.lastname: Hong
authors.forename: Seung-Woo
authors.initials: SW
authors.lastname: Suh
authors.forename: Hitesh N
authors.initials: HN
authors.lastname: Modi
authors.forename: Chang-Yong
authors.initials: CY
authors.lastname: Hur
authors.forename: Hae-Ryong
authors.initials: HR
authors.lastname: Song
authors.forename: Joo-Hyung
authors.initials: JH
authors.lastname: Ryu
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D056910:Republic of Korea; D012600:Scoliosis / Q000000981:diagnostic imaging*; D012720:Severity of Illness Index; D013131:Spine / Q000000981:diagnostic imaging*