title: Comparison of the inter- and intra-observer reproducibility of the Crowe, Hartofilakidis and modified Cochin classification systems for the diagnosis of developmental dysplasia of the hip.
abstract: BACKGROUND
  Developmental dysplasia of the hip (DDH) leads to multiple treatment challenges during adulthood. Surgical treatment is mainly based on radiographic evaluation of the anatomical alterations. Several classification systems have been described in the published English scientific literature, but the French Cochin classification has not been used very much. Its primary advantage lies in its ability to intricately describe the DDH alterations with a large number of grades. We hypothesized that the inter- and intra-observer reproducibility of the SOFCOT-modified Cochin classification system was equal to that of the Crowe and Hartofilakidis classifications.
  
  
  METHODS
  Five French orthopaedic surgeons who were DDH experts classified 94 A/P pelvis radiographs (179 hips) using the Crowe (Cr), Hartofilikadis (Ha) and modified Cochin (Co) systems. This evaluation was repeated a second time one month later. The intra-observer reproducibility was determined with weighted Kappa and concordance coefficients. The inter-observer reproducibility was performed by calculating the multirater Kappa coefficient on each of the two data series.
  
  
  RESULTS
  For the intra-observer reliability, the average weighed concordance coefficients (95% CI) were 88.62-94.52 for Cr, 89.43-93.80 for Ha and 92.14-95.71 for Co. The average weighed Kappa coefficients (95% CI) were 0.70-0.85 for Cr, 0.67-0.82 for Ha and 0.75-0.83 for Co. For the inter-observer reliability, the Kappa for each assessment round was 0.57 and 0.48 for Cr, 0.43 and 0.44 for Ha, and 0.43 and 0.37 for Co.
  
  
  CONCLUSIONS
  The intra- and inter-observer reliability for the modified Cochin classification system is the same as the one for the Crowe and Hartofilakidis classifications. The theoretical advantage of this classification system should be confirmed by comparing the findings with intra-operative anatomical observations.
  IV.
authors.affiliation: Service de chirurgie orthopédique et traumatologique, faculté de médecine, université de Bretagne-Occidentale, hôpital de la Cavale-Blanche, CHRU de Brest, boulevard Tanguy-Prigent, 29200 Brest, France.
authors.forename: A
authors.initials: A
authors.lastname: Clavé
authors.affiliation: Centre médico-chirurgical Paris V, 36, boulevard Saint-Marcel, 75005 Paris, France.
authors.forename: L
authors.initials: L
authors.lastname: Kerboull
authors.affiliation: Clinique mutualiste de la Porte-de-L'Orient, 3, rue Robert-de-La-Croix, 56324 L'Orient, France.
authors.forename: T
authors.initials: T
authors.lastname: Musset
authors.affiliation: Institut du mouvement et de l'appareil locomoteur, faculté de médecine, université d'Aix-Marseille, hôpital Sainte Marguerite, Marseille, France.
authors.forename: X
authors.initials: X
authors.lastname: Flecher
authors.affiliation: Service de chirurgie orthopédique, réparatrice et traumatologique, faculté de médecine Rennes, université de Rennes, hôpital Sud, CHRU de Rennes, 16, boulevard de Bulgarie, 35203 Rennes, France.
authors.forename: D
authors.initials: D
authors.lastname: Huten
authors.affiliation: Service de chirurgie orthopédique et traumatologique, faculté de médecine, université de Bretagne-Occidentale, hôpital de la Cavale-Blanche, CHRU de Brest, boulevard Tanguy-Prigent, 29200 Brest, France.
authors.forename: C
authors.initials: C
authors.lastname: Lefèvre
authors.affiliation: Service de chirurgie orthopédique, Hôtel-Dieu-de-Pont-l'Abbé, rue Signor, 29120 Pont-l'Abbé, France.
authors.forename: F
authors.initials: F
authors.lastname: Gaucher
authors.affiliation: Service de chirurgie orthopédique et traumatologique, faculté de médecine, université de Bretagne-Occidentale, hôpital de la Cavale-Blanche, CHRU de Brest, boulevard Tanguy-Prigent, 29200 Brest, France. Electronic address: eric.stindel@univ-brest.fr.
authors.forename: E
authors.initials: E
authors.lastname: Stindel
mesh_terms: D002648:Child; D002675:Child, Preschool; D006618:Hip Dislocation, Congenital / Q000145:classification* / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D007223:Infant; D015588:Observer Variation; D011859:Radiography; D015203:Reproducibility of Results; D009626:Terminology as Topic
keywords: Classification; Congenital hip disease; Dysplasia; Hip