title: Accuracy and reliability testing of two methods to measure internal rotation of the glenohumeral joint.
abstract: BACKGROUND
  We compared accuracy and reliability of a traditional method of measurement (most cephalad vertebral spinous process that can be reached by a patient with the extended thumb) to estimates made with the shoulder in abduction to determine if there were differences between the two methods.
  
  
  METHODS
  Six physicians with fellowship training in sports medicine or shoulder surgery estimated measurements in 48 healthy volunteers. Three were randomly chosen to make estimates of both internal rotation measurements for each volunteer. An independent observer made objective measurements on lateral scoliosis films (spinous process method) or with a goniometer (abduction method). Examiners were blinded to objective measurements as well as to previous estimates.
  
  
  RESULTS
  Intraclass coefficients for interobserver reliability for the traditional method averaged 0.75, indicating good agreement among observers. The difference in vertebral level estimated by the examiner and the actual radiographic level averaged 1.8 levels. The intraclass coefficient for interobserver reliability for the abduction method averaged 0.81 for all examiners, indicating near-perfect agreement. Confidence intervals indicated that estimates were an average of 8° different from the objective goniometer measurements. Pearson correlation coefficients of intraobserver reliability for the abduction method averaged 0.94, indicating near-perfect agreement within observers. Confidence intervals demonstrated repeated estimates between 5° and 10° of the original.
  
  
  CONCLUSIONS
  Internal rotation estimates made with the shoulder abducted demonstrated interobserver reliability superior to that of spinous process estimates, and reproducibility was high. On the basis of this finding, we now take glenohumeral internal rotation measurements with the shoulder in abduction and use a goniometer to maximize accuracy and objectivity.
authors.affiliation: Department of Orthopaedic Surgery and Biomedical Engineering, University of Tennessee-Campbell Clinic, Memphis, TN, USA.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Hall
authors.affiliation: Department of Orthopaedic Surgery and Biomedical Engineering, University of Tennessee-Campbell Clinic, Memphis, TN, USA.
authors.forename: Frederick M
authors.initials: FM
authors.lastname: Azar
authors.affiliation: Department of Orthopaedic Surgery and Biomedical Engineering, University of Tennessee-Campbell Clinic, Memphis, TN, USA.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Miller
authors.affiliation: Department of Orthopaedic Surgery and Biomedical Engineering, University of Tennessee-Campbell Clinic, Memphis, TN, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Smith
authors.affiliation: Department of Orthopaedic Surgery and Biomedical Engineering, University of Tennessee-Campbell Clinic, Memphis, TN, USA. Electronic address: tthrockmorton@campbellclinic.com.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Throckmorton
mesh_terms: D053587:Arthrometry, Articular; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D015588:Observer Variation; D011859:Radiography; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012399:Rotation; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D016037:Single-Blind Method
keywords: Glenohumeral joint; abduction method; accuracy; internal rotation; measurement; spinous process method