title: Test-retest reliability and responsiveness of centre of pressure measurements in patients with hip osteoarthritis.
abstract: OBJECTIVE
  The aim of this study was to determine a set of measures for the evaluation of balance in patients suffering from hip osteoarthritis (OA) that were both reliable and responsive to change.
  
  
  METHODS
  Three groups of subjects; Healthy, hip OA patients without surgery, and hip OA with surgery (pre and post-surgery) were included in this study. Subjects had to perform balance tests in two positions: standard and narrowed stance. CoP-based measures test-retest reliability was assessed in hip OA without surgery group, responsiveness were assessed between all groups and between pre and post-surgery.
  
  
  RESULTS
  Intraclass Correlation Coefficient (ICC) values from hip OA without surgery ranged from -0.03 to 0.9 for only five parameters (CoP path length, SD velocity, mean velocity, and antero-posterior Root Mean Square (RMS(AP)) having values over 0.7. SD velocity and RMS(AP) showed significant differences between healthy and surgery group in standard stance whereas narrowed stance revealed most differences between all groups. RMS(AP) showed the best responsiveness (Standardized Response Mean ∼0.5) between pre vs post-surgery in both conditions. RMS(AP) was also capable of discriminating between hip OA with surgery vs without surgery groups with good sensitivity and specificity.
  
  
  CONCLUSIONS
  Our results showed there to be reliability and responsiveness of five postural parameters in hip OA patients in two conditions of standing balance. More parameters were significantly different in narrowed stance whereas sensitivity was better in standard stance. SD velocity and RMS(AP) discriminate between degrees of OA severity and highlight potential balance deficits even after arthroplasty. Selected parameters during standing balance could be assessed to complete the set of quantitative measures to quantify hip OA patient deficiencies.
authors.affiliation: CIC INSERM 1432, Plateforme d'Investigation Technologique, Dijon University Hospital, Dijon, France; INSERM U1093, University of Burgundy, Dijon, France. Electronic address: davy.laroche@chu-dijon.fr.
authors.forename: D
authors.initials: D
authors.lastname: Laroche
authors.affiliation: INSERM U1093, University of Burgundy, Dijon, France.
authors.forename: A
authors.initials: A
authors.lastname: Kubicki
authors.affiliation: Neural Control of Movement Laboratory, School of Medicine, Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Stapley
authors.affiliation: CIC INSERM 1432, Plateforme d'Investigation Technologique, Dijon University Hospital, Dijon, France; INSERM U1093, University of Burgundy, Dijon, France; Department of Physical Medicine and Rehabilitation, Dijon University Hospital, Dijon, France.
authors.forename: V
authors.initials: V
authors.lastname: Gremeaux
authors.affiliation: Department of General Medicine, Faculty of Medicine, University of Burgundy, Dijon, France.
authors.forename: K
authors.initials: K
authors.lastname: Mazalovic
authors.affiliation: INSERM U1093, University of Burgundy, Dijon, France; Department of Rheumatology, Dijon University Hospital, Dijon, France.
authors.forename: J-F
authors.initials: JF
authors.lastname: Maillefert
authors.affiliation: INSERM U1093, University of Burgundy, Dijon, France; Department of Rheumatology, Dijon University Hospital, Dijon, France.
authors.forename: P
authors.initials: P
authors.lastname: Ornetti
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Hip; Osteoarthritis; Reliability; Responsiveness; Standing balance