title: Interobserver Agreement of the Eaton-Glickel Classification for Trapeziometacarpal and Scaphotrapezial Arthrosis.
abstract: OBJECTIVE
  To determine whether simplification of the Eaton-Glickel (E-G) classification of trapeziometacarpal (TMC) joint arthrosis (eliminating evaluation of the scaphotrapezial [ST] joint) and information about the patient's symptoms and examination influence interobserver reliability. We also tested the null hypotheses that no patient and/or surgeon factors affect radiographic rating of TMC joint arthrosis and that no surgeon factors affect the radiographic rating of ST joint arthrosis.
  
  
  METHODS
  In an on-line survey, 92 hand surgeons rated TMC joint arthrosis and ST joint arthrosis separately on 30 radiographs (Robert, true lateral, and oblique views) according to the (modified) E-G classification. We randomly assigned 42 observers to review radiographs alone and also informed 50 of the patient's symptoms and examination. Information about symptoms and examination was randomized. Interobserver reliability was determined with the s* statistic. Because of the hierarchical data structure, cross-classified ordinal multilevel regression analyses were performed to identify factors associated with the severity of arthrosis.
  
  
  RESULTS
  Shortening the E-G classification to the first 3 stages significantly improved the interobserver reliability, which approached substantial agreement. Providing clinical information to observers marginally improved interobserver reliability. Factors associated with a lower E-G stage for TMC joint arthrosis, among observers who rated the severity of TMC joint arthrosis based on radiographs and clinical information, included female surgeon, practice setting, supervising surgical trainees in the operating room, self-reported number of patients with TMC joint arthrosis typically treated annually, male patient, higher patient age, pain limiting daily activities, and shoulder sign. A self-reported larger number of patients with TMC joint arthrosis treated annually was the only variable associated with a higher modified E-G classification to rate ST joint arthrosis.
  
  
  CONCLUSIONS
  Our findings suggest that simpler classifications that focus on a single anatomical area are reliable and that surgeon and patient factors can bias interpretation of objective pathophysiology such as radiographic findings.
  
  
  METHODS
  Diagnostic III.
authors.affiliation: Department of Plastic, Reconstructive, and Hand Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Orthopaedic Hand and Upper Extremity Service, Harvard Medical School, Massachusetts General Hospital, Boston, MA.
authors.forename: Stéphanie J E
authors.initials: SJ
authors.lastname: Becker
authors.affiliation: Department of Surgery, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Wendy E
authors.initials: WE
authors.lastname: Bruinsma
authors.affiliation: Orthopaedic Research Center Amsterdam, Department of Orthopaedic Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Thierry G
authors.initials: TG
authors.lastname: Guitton
authors.affiliation: Department of Plastic, Reconstructive, and Hand Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Chantal M A M
authors.initials: CM
authors.lastname: van der Horst
authors.affiliation: Department of Plastic, Reconstructive, and Hand Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Simon D
authors.initials: SD
authors.lastname: Strackee
authors.affiliation: Orthopaedic Hand and Upper Extremity Service, Harvard Medical School, Massachusetts General Hospital, Boston, MA. Electronic address: dring@partners.org.
authors.forename: David
authors.initials: D
authors.lastname: Ring
mesh_terms: D000328:Adult; D052737:Carpometacarpal Joints / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000145:classification* / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012720:Severity of Illness Index
keywords: Classification agreement; interobserver reliability; osteoarthritis; scaphotrapezial arthrosis; trapeziometacarpal arthrosis