title: Diurnal variation on balance control in patients with symptomatic knee osteoarthritis.
abstract: OBJECTIVE
  Increasing evidence supports balance control impairment in older adult patients with knee osteoarthritis (OA). However, there is limited data on diurnal variation of balance control in these patients. This study aimed to investigate postural stability in older adult patients with symptomatic knee OA during different periods in a daytime.
  
  
  METHODS
  Two-hundred and forty-one patients with OA knee (median age=65 ± 12 years; 82 males) were enrolled in this study. Static posturography was performed under four standing conditions: eyes open and eyes closed, without and with foam support. To assess diurnal postural variations, testing sessions were defined as follows: 8-10 am, 10-12 am, 1 pm-3 pm, 3 pm-5 pm. Influence of sex, age, height, weight, and body mass index on postural stability was evaluated. Knee pain was also assessed in these four testing sessions.
  
  
  RESULTS
  Postural control was in particular less efficient in the late morning than in the early afternoon (p<0.05). Diurnal variation of balance control was more noticeable in older, heavier, and male patients (p<0.05). Patients' knee pain was more pronounced in the morning than in the afternoon (p<0.001).
  
  
  CONCLUSIONS
  Balance stability of patients with OA knee was different during a daytime. Altered postural performance in the morning could be explained by joint pain. This diurnal variation should be taken into account in the daily management of knee OA.
authors.affiliation: Université de Lorraine, EA 3450, Development, Adaptation and Disadvantage, Faculty of Medicine and UFR STAPS, F-54600 Villers-lès-Nancy, France; Department of Orthopaedics, Renmin Hospital of Wuhan University, 430060 Wuhan, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Université de Lorraine, EA 3450, Development, Adaptation and Disadvantage, Faculty of Medicine and UFR STAPS, F-54600 Villers-lès-Nancy, France; Laboratory for the Analysis of Posture, Equilibrium and Motor Function (LAPEM), University Hospital of Nancy, F-54500 Vandoeuvre-lès-Nancy, France; Sports Medicine Research Laboratory, Luxembourg Institute of Health, L-1460 Luxembourg, Luxembourg.
authors.forename: Alexis
authors.initials: A
authors.lastname: Lion
authors.affiliation: Department of Rheumatology, University Hospital of Nancy, F-54511, Vandoeuvre-lès-Nancy, France; IMoPA UMR-CNRS, 7365, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Chary-Valckenaere
authors.affiliation: Department of Rheumatology, University Hospital of Nancy, F-54511, Vandoeuvre-lès-Nancy, France; IMoPA UMR-CNRS, 7365, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Loeuille
authors.affiliation: Department of Rheumatology, University Hospital of Nancy, F-54511, Vandoeuvre-lès-Nancy, France; IMoPA UMR-CNRS, 7365, France; INSERM, CIC-EC, CIE6, Nancy F-54 000, France.
authors.forename: Anne-Christine
authors.initials: AC
authors.lastname: Rat
authors.affiliation: Université de Lorraine, EA 3450, Development, Adaptation and Disadvantage, Faculty of Medicine and UFR STAPS, F-54600 Villers-lès-Nancy, France; Regional Institute of Physical Medicine and Rehabilitation, F-54042 Nancy cedex, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Paysant
authors.affiliation: Université de Lorraine, EA 3450, Development, Adaptation and Disadvantage, Faculty of Medicine and UFR STAPS, F-54600 Villers-lès-Nancy, France; Laboratory for the Analysis of Posture, Equilibrium and Motor Function (LAPEM), University Hospital of Nancy, F-54500 Vandoeuvre-lès-Nancy, France; Department of Oto-Rhino-Laryngology, University Hospital of Nancy, F-54500, Vandoeuvre-lès-Nancy, France. Electronic address: Philippe.Perrin@univ-lorraine.fr.
authors.forename: Philippe P
authors.initials: PP
authors.lastname: Perrin
mesh_terms: D000368:Aged; D015992:Body Mass Index; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D020370:Osteoarthritis, Knee / Q000503:physiopathology* / Q000534:rehabilitation; D004856:Postural Balance / Q000502:physiology*
keywords: Balance control; Diurnal variation; Knee osteoarthritis; NCT01544647; Older adult patient; Posturography