title: Inter-observer reproducibility of measurements of range of motion in patients with shoulder pain using a digital inclinometer.
abstract: BACKGROUND
  Reproducible measurements of the range of motion are an important prerequisite for the interpretation of study results. The digital inclinometer is considered to be a useful instrument because it is inexpensive and easy to use. No previous study assessed inter-observer reproducibility of range of motion measurements with a digital inclinometer by physical therapists in a large sample of patients.
  
  
  METHODS
  Two physical therapists independently measured the passive range of motion of the glenohumeral abduction and the external rotation in 155 patients with shoulder pain. Agreement was quantified by calculation of the mean differences between the observers and the standard deviation (SD) of this difference and the limits of agreement, defined as the mean difference +/- 1.96*SD of this difference. Reliability was quantified by means of the intraclass correlation coefficient (ICC).
  
  
  RESULTS
  The limits of agreement were 0.8 +/- 19.6 for glenohumeral abduction and -4.6 +/- 18.8 for external rotation (affected side) and quite similar for the contralateral side and the differences between sides. The percentage agreement within 10 degrees for these measurements were 72% and 70% respectively. The ICC ranged from 0.28 to 0.90 (0.83 and 0.90 for the affected side).
  
  
  CONCLUSIONS
  The inter-observer agreement was found to be poor. If individual patients are assessed by two different observers, differences in range of motion of less than 20-25 degrees can not be distinguished from measurement error. In contrast, acceptable reliability was found for the inclinometric measurements of the affected side and the differences between the sides, indicating that the inclimeter can be used in studies in which groups are compared.
authors.affiliation: Institute for Research in Extramural Medicine, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands. a.f.de.winter@med.rug.nl
authors.forename: Andrea F
authors.initials: AF
authors.lastname: de Winter
authors.forename: Monique A M B
authors.initials: MA
authors.lastname: Heemskerk
authors.forename: Caroline B
authors.initials: CB
authors.lastname: Terwee
authors.forename: Marielle P
authors.initials: MP
authors.lastname: Jans
authors.forename: Walter
authors.initials: W
authors.lastname: Devillé
authors.forename: Dirk-Jan
authors.initials: DJ
authors.lastname: van Schaardenburg
authors.forename: Rob J P M
authors.initials: RJ
authors.lastname: Scholten
authors.forename: Lex M
authors.initials: LM
authors.lastname: Bouter
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010147:Pain Measurement; D010808:Physical Examination / Q000295:instrumentation*; D026741:Physical Therapy Modalities / Q000295:instrumentation*; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012399:Rotation; D020069:Shoulder Pain / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted