title: Joint proprioception, muscle strength, and functional ability in patients with osteoarthritis of the knee.
abstract: OBJECTIVE
  To test the hypotheses that poor knee joint proprioception is related to limitations in functional ability, and poor proprioception aggravates the impact of muscle weakness on limitations in functional ability in osteoarthritis (OA) of the knee.
  
  
  METHODS
  Sixty-three patients with symptomatic OA of the knee were tested. Proprioceptive acuity was assessed by establishing the joint motion detection threshold (JMDT) in the anteroposterior direction. Muscle strength was measured using a computer-driven isokinetic dynamometer. Functional ability was assessed by the 100-meter walking test, the Get Up and Go (GUG) test, and the Western Ontario and McMaster Universities Osteoarthritis Index physical function (WOMAC-PF) questionnaire. Correlation analyses were performed to assess the relationship between proprioception, muscle strength, and functional ability. Regression analyses were performed to assess the impact of proprioception on the relationship between muscle strength and functional ability.
  
  
  RESULTS
  Poor proprioception (high JMDT) was related to more limitation in functional ability (walking time r = 0.30, P < 0.05; GUG time r = 0.30, P < 0.05; WOMAC-PF r = 0.26, P <0.05). In regression analyses, the interaction between proprioception and muscle strength was significantly related to functional ability (walking time, P < 0.001 and GUG time, P < 0.001) but not to WOMAC-PF score (P = 0.625). In patients with poor proprioception, reduction of muscle strength was associated with more severe deterioration of functional ability than in patients with accurate proprioception.
  
  
  CONCLUSIONS
  Patients with poor proprioception show more limitation in functional ability, but this relationship is rather weak. In patients with poor proprioception, muscle weakness has a stronger impact on limitations in functional ability than in patients with accurate proprioception.
authors.affiliation: Jan van Breemen Institute, Amsterdam, The Netherlands. M.van.der.Esch@planet.nl
authors.forename: M
authors.initials: M
authors.lastname: van der Esch
authors.forename: M
authors.initials: M
authors.lastname: Steultjens
authors.forename: J
authors.initials: J
authors.lastname: Harlaar
authors.forename: D
authors.initials: D
authors.lastname: Knol
authors.forename: W
authors.initials: W
authors.lastname: Lems
authors.forename: J
authors.initials: J
authors.lastname: Dekker
mesh_terms: D000368:Aged; D004185:Disability Evaluation; D005080:Exercise Test; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology*; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology*; D020370:Osteoarthritis, Knee / Q000150:complications / Q000503:physiopathology*; D011434:Proprioception / Q000502:physiology*; D011859:Radiography; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D016138:Walking