title: Association of postural control with muscle strength, proprioception, self-reported knee instability and activity limitations in patients with knee osteoarthritis.
abstract: OBJECTIVE
  To determine the association of postural control with muscle strength, proprioception, self-reported knee instability and activity limitations in patients with knee osteoarthritis.
  
  
  METHODS
  A total of 284 patients with knee osteoarthritis from the Amsterdam Osteoarthritis cohort were included. Postural control was assessed using the One-Leg Stand Test (OLST), in which the patients were asked to stand on one leg for 30 s. Muscle strength (isokinetic dynamometer), proprioception (joint motion detection threshold) and self-reported knee instability (episodes of buckling, shifting or giving way) were also assessed. Activity limitations were assessed using the Get Up and Go (GUG) test, the walking up-down stairs test, and Western Ontario and McMaster University Osteoarthritis Index - Physical Function subscale. Regression analyses were used to assess the associations.
  
  
  RESULTS
  Muscle weakness (p = 0.02) and proprioceptive inaccuracy (p < 0.001) were associated with decreased postural control. Decreased postural control was associated with less time performing the GUG test (p < 0.001) and the walking up-down stairs test (p < 0.001). These associations were found after adjustment for relevant confounders.
  
  
  CONCLUSIONS
  In patients with knee osteoarthritis, decreased postural control is associated with muscle weakness, proprioceptive inaccuracy and performance-based activity limitations. These results highlight the importance of including assessment and training of postural control in this group of patients.
authors.affiliation: Amsterdam Rehabilitation Research Center, Reade, The Netherlands. d.c.sanchezramirez@vu.nl
authors.forename: Diana C
authors.initials: DC
authors.lastname: Sanchez-Ramirez
authors.forename: Marike
authors.initials: M
authors.lastname: van der Leeden
authors.forename: Dirk L
authors.initials: DL
authors.lastname: Knol
authors.forename: Martin
authors.initials: M
authors.lastname: van der Esch
authors.forename: Leo D
authors.initials: LD
authors.lastname: Roorda
authors.forename: Sabine
authors.initials: S
authors.lastname: Verschueren
authors.forename: Jaap
authors.initials: J
authors.lastname: van Dieën
authors.forename: Willem F
authors.initials: WF
authors.lastname: Lems
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D015331:Cohort Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000209:etiology*; D007717:Knee / Q000502:physiology; D007719:Knee Joint / Q000502:physiology; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D009068:Movement; D053580:Muscle Strength; D018908:Muscle Weakness; D009426:Netherlands; D020370:Osteoarthritis, Knee / Q000150:complications*; D004856:Postural Balance / Q000502:physiology; D011187:Posture / Q000502:physiology; D011434:Proprioception; D012044:Regression Analysis; D057566:Self Report; D012720:Severity of Illness Index; D016138:Walking