title: Test-retest reliability of 3D ultrasound measurements of the thoracic spine.
abstract: OBJECTIVE
  To explore the reliability of the Zebris CMS 20 ultrasound analysis system with pointer application for measuring end-range flexion, end-range extension, and neutral kyphosis angle of the thoracic spine.
  
  
  METHODS
  The study was performed within the School of Physiotherapy in cooperation with the Orthopedic Department at a University Hospital.
  
  
  METHODS
  The thoracic spines of 28 healthy subjects were measured.
  
  
  METHODS
  Measurements for neutral kyphosis angle, end-range flexion, and end-range extension were taken once at each time point. The bone landmarks were palpated by one examiner and marked with a pointer containing 2 transmitters using a frequency of 40 kHz. A third transmitter was fixed to the pelvis, and 3 microphones were used as receiver. The real angle was calculated by the software. Bland-Altman plots with 95% limits of agreement, intraclass correlations (ICC), standard deviations of mean measurements, and standard error of measurements were used for statistical analyses. The test-retest reliability in this study was measured within a 24-hour interval.
  
  
  METHODS
  Statistical parameters were used to judge reliability.
  
  
  RESULTS
  The mean kyphosis angle was 44.8° with a standard deviation of 17.3° at the first measurement and a mean of 45.8° with a standard deviation of 16.2° the following day. The ICC was high at 0.95 for the neutral kyphosis angle, and the Bland-Altman 95% limits of agreement were within clinical acceptable margins. The ICC was 0.71 for end-range flexion and 0.34 for end-range extension, whereas the Bland-Altman 95% limits of agreement were wider than with the static measurement of kyphosis. Compared with static measurements, the analysis of motion with 3-dimensional ultrasound showed an increased standard deviation for test-retest measurements.
  
  
  CONCLUSIONS
  The test-retest reliability of ultrasound measuring of the neutral kyphosis angle of the thoracic spine was demonstrated within 24 hours. Bland-Altman 95% limits of agreement and the standard deviation of differences did not appear to be clinically acceptable for measuring flexion and extension.
authors.affiliation: Department of Orthopedics and Rheumatology, University Hospital Marburg, Marburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Fölsch
authors.forename: Stefanie
authors.initials: S
authors.lastname: Schlögel
authors.forename: Stefan
authors.initials: S
authors.lastname: Lakemeier
authors.forename: Udo
authors.initials: U
authors.lastname: Wolf
authors.forename: Nina
authors.initials: N
authors.lastname: Timmesfeld
authors.forename: Adrian
authors.initials: A
authors.lastname: Skwara
mesh_terms: D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007738:Kyphosis / Q000000981:diagnostic imaging*; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging*; D014463:Ultrasonography